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1 Table of Contents Polarization Components Polarizers NEW Retarders NEW NEW Linear Polarizer Principles 3 Precision Linear Polarizers 6 High Contrast Linear Polarizers 8 Ultra-High Contrast Linear Polarizers 9 VersaLight Polarizers 11 Laser Line Beamsplitting Polarizers 14 Broadband Beamsplitting Polarizers 15 UV Optics 17 Glan-Thompson Polarizers 18 Optical Isolation with Circular Polarizers 19 Dichroic Circular Polarizers 20 Beam Separators 21 Polarizer Selection Chart 22 Retarder Principles 24 Polarization Control with Polymers 26 Polarization Manipulation with Retarders 27 Polarization Analysis Example 28 Compound Zero Order Quartz Retarders 29 Precision Retarders 30 Commercial Retarders 32 Wide Field Retarders 33 Dual Wavelength Retarders 35 Precision Achromatic Retarders 37 Bi-Crystalline Achromatic Retarders 38 Retarder Selection Chart 40 Polarizer/Retarder Sets 42 Mounting Hardware NEW Rotary Mounts 43 Beamsplitting Cube Mounts 44 Devices NEW NEW NEW Polarization Control with s 45 Custom Capabilities 46 Variable Retarders 48 Variable Attenuators 51 Polarization Rotators 53 High Contrast Optical Shutters 55 Swift Principles 56 Swift Variable Retarders 57 NEW Swift Optical Shutters 58 Drive Electronics NEW NEW Basic Controller 59 Four Channel Digital Interface 60 Two Channel High Voltage Interface 62 Systems Spatial Light Modulators Spatial Light Modulator Principles 64 Spatial Light Modulators 65 Spatial Light Modulator Controller 66 Tunable Optical Filters Tunable Optical Filter Principles 68 Tunable Optical Filters 70 Polarimeters Polarimeters 72 Eigenstate Generator Set 74 Engineering Services Capabilities 76 Optical Assemblies 76 Quality Standards 79 Ordering Information 80 Table of Contents Member of the Colorado Photonics Industry Association, Inc Meadowlark Optics, Inc. All rights reserved. LabVIEW and National Instruments are trademarks of National Instruments Corporation. Microsoft and Windows are trademarks of Microsoft Corporation. Polarcor is a trademark of Corning, Inc. MicroWires is a trademark of Moxtek, Inc. VersaLight is a trademark of Meadowlark Optics, Inc. CAGE Code: 3Z151 mlo@meadowlark.com (303)

2 Polarization Components Polarization components provide the backbone of our business. Polarizers, Retarders and Devices are the fundamental building blocks for our line of systems and instrumentation and also for our original equipment manufacturer (OEM) customers. In addition to the delivered hardware components, an important part of the service Meadowlark Optics provides to our customers includes extensive, precise polarization metrology. Our metrological capability ensures that these components are delivered to you in spec the first time, every time. We have broadened our offering to include Polarizers for the ultraviolet to the mid-infrared regions of the spectrum. Retarders (or waveplates) are another key component to Meadowlark Optics customers. Recent new products include Wide Field Retarders, which provide excellent field of view performance out to 30 degrees incidence, or more. Now, we are introducing Dual Wavelength Retarders for polarization control at two fixed wavelengths. The Polarizers and Retarders described above are passive components, with no active control possible. Our line of Devices includes compensated and uncompensated LC Variable Retarders, Attenuators and Polarization Rotators. With this catalog, we are now introducing Optical Shutters, as well. Naturally, Meadowlark Optics offers necessary control electronics to mate with the LC Device required in your application including the offering of an extended warranty program. A line of Mounting Hardware is also available. We ve added Beamsplitter Mounts to our popular Rotary Mount offering. Additionally, we provide the capability for the assembly and calibration of Optical Sub-assemblies giving our customers a valuable, time saving and quality improved product. Call for more information. mlo@meadowlark.com (303)

3 Linear Polarizer Principles Fig. 1-1 Regardless of input polarization, a linear polarizer transmits only linearly polarized light. Ideal linear polarizers allow the transmission of only one polarization state with zero leakage of all other polarization states. Rotating the linear polarizer about the optical axis changes the output plane of polarization. Thus, a perfect linear polarizer transmits only 50% of an unpolarized input beam and two perfect polarizers with their transmission axes crossed totally extinguish an incident beam. Imperfections in polarizers such as scattering sites, material defects (such as pinholes in thin films) and field-of-view effects reduce ideal polarizers contrast. When choosing a linear polarizer, several key factors must be considered including: cost, wavelength range, aperture size, acceptance angle, damage threshold, transmission efficiency and extinction ratio. Extinction ratio (or contrast ratio) is defined as the ratio of transmitted intensity through parallel polarizers to the transmitted intensity through crossed polarizers. Meadowlark Optics offers polarizers with extinction ratios as high as 10,000,000:1 over the operating wavelength range. Meadowlark Optics now offers four types of linear polarizers: dichroic (polymer and glass), dielectric beamsplitting, wire grid and calcite crystal. Dichroic Polarizers Polymer and Glass Meadowlark Optics offers an extensive line of dichroic polarizers made from both polymer and treated glass materials. Dichroic refers to the selective polarization absorption of the anisotropic polarizing material (Diattenuation). These polarizers are usually constructed by laminating a thin, stretched and dyed polymer film between two polished and antireflection-coated glass windows. The resulting compact component offers excellent value and is often the best choice for flux densities below 1 watt/cm 2. Selecting the appropriate dichroic polarizing material enables excellent extinction ratio performance over the wavelength range from 310 to 5000 nm. Due to small variations in the polarization material, extinction ratios degrade over larger apertures for all dichroic polarizers. Meadowlark Optics has improved the transmission of dichroic polarizers with high-efficiency, broadband antireflection coatings on the glass windows used in our product design. Laminated glass construction contributes to a substantial improvement in transmitted wavefront distortion. Our polarizer assembly greatly improves the product durability, allowing for easy and repeated cleaning. Meadowlark Optics also offers a line of high contrast dichroic glass polarizers for the near and mid infrared regions of the spectrum up to 5000 nm. High throughput and contrast make these polarizers an excellent choice for near infrared requirements. Key advantages of dichroic polarizers include superior angular acceptance and extreme flexibility for custom shapes and sizes. Please call one of our Sales Engineers for assistance. Beamsplitting Polarizers Beamsplitting polarizers divide unpolarized incident light into two (usually) orthogonal, linearly polarized beams. Low absorption coatings provide an excellent combination of damage resistance and extinction ratio at a moderate price. Rugged beamsplitter cubes are easily mounted and therefore designed into many instrument applications. Beamsplitting polarizers offer the unique advantage of providing two linearly polarized output beams, one transmitting straight through and the second splitting off at precisely 90 degrees. When necessary, the extinction ratio of the reflected beam can be dramatically improved by adding a dichroic polarizer to the output face. Meadowlark Optics offers both Laser Line and Broadband Beamsplitting Polarizers, covering visible to near infrared applications. Laser Line Beamsplitting Polarizers offer the advantage of V-type antireflection coatings, improving efficiency by limiting surface losses. Broadband Beamsplitting Polarizers are more versatile for tunable wavelength or broadband sources. Note: Polarizers are available from less than 5mm square to 200 mm and greater diameter Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

4 Polarizers Retarders Linear Polarizer Principles Calcite Polarizers Calcite is a naturally occurring birefringent crystal with excellent polarization properties including very high extinction ratio and transmission efficiency. Aperture sizes are limited, since large optically uniform pieces of this natural crystal are rare. Calcite material exhibits extremely broadband transmission performance, from 320 to 2300 nm. Meadowlark Optics offers Glan-Thompson calcite polarizers. Manufactured from Grade A optical calcite material, the design takes advantage of total internal reflection to separate the two polarization components. Glan-Thompson Polarizers are recommended where a wide acceptance angle is important for overall system performance. However, the version with cemented construction limits both power handling and ultraviolet performance. Mounting Hardware Devices Fig. 1-2 Beamsplitting Polarizers provide two orthogonally polarized beams, conveniently separated by 90. Wire Grid Polarizers VersaLight wire grid polarizers are the modern outgrowth of the 1888 experiments by Heinrich Hertz using fine metallic wires wrapped around a non-conductive frame. Instead of manually arranging an array of fine conductive wires, lithographic techniques are used to place sub 100 nm pitch aluminum conductors on glass substrates. When incident unpolarized radiation interacts with the wire grid, differences in boundary conditions drive different behavior for the two orthogonal polarizations. Electromagnetic radiation incident on the wires oscillate free electrons which have a much higher mobility along the wires than in the transverse dimension. Ideally, the wires behave as a perfect reflector for the parallel field and pass 100% of the transverse field. Material defects and Joule heating reduce the contrast of the polarizer, which is also strongly affected by the wavelength of the light passing through it. (Longer wavelengths are closer approximations to the ideal solution as their wavelengths become much greater than the wire grid spacing.) Versalight polarizers are available in large aperture sizes up to 200mm diameter with high contrast across the visible and near infrared spectrum. They can handle relatively high power and are more durable when coated. Specially selected ultraviolet transmissive material is available on a custom basis. Please contact a Meadowlark Optics Sales Engineer for assistance. 4 (303) mlo@meadowlark.com

5 Linear Polarizer Principles Polarizer and Retarder References: 1. T. Baur and S. McClain, Polarization Issues in Optical Design in Optical System Design, edited by Robert Fischer, (SPIE press, McGraw-Hill, 2008), Chap J.M. Bennett, Polarization, in Handbook of Optics, edited by M. Bass, (McGraw-Hill, New York, 1995), Vol. I, Chap. 5; J.A. Dobrowolski, Optical Properties of Films and Coatings, ibid., Vol. I, Chap. 42; J.M.Bennett, Polarizers, ibid., Vol. II, Chap. 3; S. Wu, s, ibid., Vol. II, Chap D. Clarke and J.F. Grainger, Polarized Light and Optical Measurement, (Pergamon Press, New York, 1971). 4. D.S. Kliger, J.W. Lewis and C.E. Randall, Polarized Light in Optics and Spectroscopy, (Academic Press, San Diego, Calif., 1990). 5. W.A. Shurcliff, Polarized Light: Production and Use, (Harvard University Press, Cambridge, Mass., 1966). 6. D.A. Holmes, Exact Theory of Retardation Plates, J.Opt. Soc. Am. 54, 1115 (1964). 7. P.D. Hale and G.W. Day, Stability of Birefringent Linear Retarders (Waveplates), Appl. Opt. 27 (24), 5146 (1988). 8. D. Malacara, Optical Shop Testing, (John Wiley and Sons, New York, 1978). 9. G. Love, Wave-front Correction and Production of Zernike Modes with a Liquid-Crystal Spatial Light Modulator, Appl. Opt. 36 (7), 1517 (1997). Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

6 Precision Linear Polarizers Polarizers Key Benefits High extinction ratios Excellent surface quality Wide angular acceptance Low transmitted wavefront distortion Ultraviolet, visible, near infrared wavelengths Retarders Extinction ratios in figures are measured against a Glan-Thompson polarizer. Mounting Hardware Devices Polarized Transmission (%) Wavelength (nm) Extinction Ratio Polarized Transmission (%) Fig. 1-3 Ultraviolet polarizer performance, specify UV1 Fig. 1-4 Visible polarizer performance, specify VIS Wavelength (nm) 100,000 10,000 1, Extinction Ratio Polarized Transmission (%) Polarized Transmission (%) Wavelength (nm) 100,000 10,000 1, Extinction Ratio Fig. 1-5 Near infrared polarizer 1 performance, specify NIR1 Fig. 1-6 Near infrared polarizer 2 performance, specify NIR2 6 (303) mlo@meadowlark.com

7 Precision Linear Polarizers Meadowlark Optics manufactures Precision Linear Polarizers using dichroic sheet polarizer material laminated between high quality glass substrates (BK 7 material, λ/10 flat). For visible wavelength polarizers, this construction produces a total transmitted wavefront distortion of less than λ/5. We use various polarizer materials to cover wavelengths between 320 and 2000 nm. Both visible and near infrared polarizers are supplied with a high-efficiency, broadband antireflection (AR) coating; single-layer AR coatings are optional on our ultraviolet polarizers. Specifications Polarizer Material Substrate Material Ultraviolet Visible Near Infrared Dichroic Polymer Transmitted Wavefront Distortion (at nm) Ultraviolet Visible Near Infrared Surface Quality Beam Deviation Ultraviolet Visible Near Infrared UV Grade Synthetic Fused Silica BK 7 Grade A, fine annealed BK 7 Grade A, fine annealed λ/2 λ/5 λ/ scratch and dig 2 arc min 1 arc min 2 arc min Reflectance (per surface, at normal incidence) Ultraviolet Visible Near Infrared Diameter Tolerance Mounted Unmounted Thickness Tolerance Storage Temperature Range Ultraviolet Visible Near Infrared Recommended Safe Operating Limit ~ 4.25% (uncoated) 0.5% 0.5% ±0.005 in. +0/ in. ±0.020 in. -50 C to +50 C -50 C to +50 C -50 C to +40 C 1 W/cm 2, CW 200 mj/cm 2, 20 ns, visible 2 J/cm 2, 20 ns, 1064 nm Prolonged exposure to strong ultraviolet radiation may damage these polarizers. Custom coatings are available. Please contact your Meadowlark Optics sales engineer for a custom quote. Both mounted and unmounted Precision Linear Polarizers are offered as standard products. Meadowlark Optics Precision Linear Polarizers have their transmission axis clearly marked. Ordering Information Diameter Clear Aperture Mounted Thickness Part Number DPM-050-UV DPM-050-VIS DPM-050-NIR DPM-050-NIR2-n DPM-100-UV DPM-100-VIS DPM-100-NIR DPM-100-NIR2-n DPM-200-UV DPM-200-VIS DPM-200-NIR DPM-200-NIR2-n Diameter Clear Aperture Unmounted Thickness Part Number DP-050-UV DP-050-VIS DP-050-NIR DP-050-NIR2-n DP-100-UV DP-100-VIS DP-100-NIR DP-100-NIR2-n Custom AR coatings are available on all polarizers. For NIR2 polarizers, please choose from the following AR coating options: NIR2 1 covers nm NIR2 2 covers nm NIR2 3 covers nm Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

8 Devices Mounting Hardware Retarders Polarizers High Contrast Linear Polarizers Fig. 1-7 Typical transmission for a High Contrast Linear Polarizer centered at 800 nm. Extinction ratio is measured a Glan-Thompson polarizer Key Benefits High Contrast High Transmission Absorptive Dichroic Glass In response to the need for improved contrast in the near infrared region, Meadowlark Optics now offers a line of High Contrast Linear Polarizers. These polarizers are constructed by laminating Polarcor dichroic glass polarizers between high quality glass substrates to achieve superior wavefront performance and surface quality. Meadowlark Optics High Contrast Linear Polarizers offer the performance of calcite polarizers in large apertures. Contrast ratios are available as high as 10,000:1. Custom wavelength ranges from 630 to 1580 nm with 60 to 80 nm bandpasses and sizes from 10 to 25 mm are available. Please contact a Meadowlark Optics Sales Engineer to discuss your specific application. Specifications Polarizer Material Substrate Material Transmitted Wavefront Distortion (at nm) Surface Quality Beam Deviation Reflectance (per surface) Temperature Range Recommended Safe Operating Limit Dichroic Glass BK 7 Grade A, fine annealed λ/ scratch and dig 3 arc min 0.5% at normal incidence -50 C to +70 C 1 W/cm 2, CW 200 mj/cm 2, 20 ns, visible 2 J/cm 2, 20 ns, 1064 nm Prolonged exposure to strong ultraviolet radiation may damage these polarizers. Ordering Information Diameter Clear Aperture Thickness Wavelength Range Part Number specify PPM λ specify PPM λ Custom sizes are available. Please contact your Meadowlark Optics sales engineer for assistance. 8 (303) mlo@meadowlark.com

9 Ultra-High Contrast Linear Polarizers Specifications Polarizer Material Substrate Material Ultraviolet Visible Infrared Long near-infared Transmitted Wavefront Distortion (at 632.8nm) Surface Quality Beam Deviation Reflectance (per surface) Diameter Tolerance Mounted Unmounted Temperature Range * Laminated Dichroic Glass Borofloat glass D263T display float glass D263T display float glass Design dependent 1λ per 10mm diameter scratch and dig 5 arc min ~ 4.25% at normal incidence ±0.005 in. +0/ in. -20 C to +50 C Specifications above are for laminated Ultra-high contrast polarizers. For unlaminated parts, please contact your Meadowlark Optics Sales Engineer. * unlaminated parts can survive -50 C to +400 C Key Benefits Extremely high contrast greater than 10,000,000:1 Unlaminated part usable to 400 C Wavelength ranges 340 to 5000 nm Absorptive Dichroic Glass If you need extremely high contrast polarizers, then Meadowlark Optics now has the solution for you. Our UHP- UV series polarizers offer high contrast in the UV from 360 to 400 nm and our UHP-LNIR series polarizers offer high contrast over the exceptionally broad range from 650 to 5000 nm. Ordering Information Diameter Mounted and Laminated Clear Aperture Thickness Part Number UPM UV UPM VIS UPM IR UPM LNIR UPM UV UPM VIS UPM IR UPM LNIR Diameter Unmounted and Laminated Clear Aperture Thickness Part Number UHP UV UHP VIS UHP IR UHP LNIR UHP UV UHP VIS UHP IR UHP LNIR Custom anti-reflection coating options are available. Please call your Meadowlark Optics Sales Engineer for assistance. For example: UV covers nm with R 1.0% IR-AR1 covers nm with R 0.5% IR-AR2 covers nm with R 0.5% IR-AR3 covers nm with R 0.5% IR-AR4 covers nm with R 0.5% Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

10 Ultra-High Contrast Linear Polarizers Devices Retarders Polarizers Fig. 1-8 Ultra-High Contrast UV Polarizer Fig. 1-9 Ultra-High Contrast VIS Polarizer Mounting Hardware Fig Ultra-High Contrast IR Polarizer Fig Ultra-High Contrast LNIR Polarizer 10 (303)

11 VersaLight Polarizers Key Benefits Broadband use Reflective polarizer Large acceptance angle VersaLight is constructed of a thin layer of aluminum MicroWires on a glass substrate and sets a new standard for applications requiring high durability, contrast and a wide field of view from the visible through infrared wavelengths, including the telecom region. VersaLight offers the performance quality of dichroic sheet polarizers while extending the operating temperature to 200 C. The nature of VersaLight s MicroWire construction allows it to perform as an exceptional polarizing beam splitter. In operation, VersaLight reflects one polarization state and transmits another, both with high contrast. VersaLight offers the broadest band and highest field of view of any material currently available. VersaLight can be shaped as needed and stacked to achieve very high contrast ratios. Large aperture VersaLight Polarizers are available on a custom basis, up to 8" rounds. Polarizers Retarders Mounting Hardware Fig Transm itted VersaLight Polarizer construction and use Fig Typical UV VersaLight Polarizer performance Devices Fig Typical NIR VersaLight Polarizer performance Fig Typical IR VersaLight Polarizer performance mlo@meadowlark.com (303)

12 VersaLight Polarizers Devices Mounting Hardware Retarders Polarizers Specifications Substrate Material Ultraviolet UV grade fused silica Near Infrared Precision float glass Infrared Precision float glass Typical contrast in reflection > 30:1 Thickness Ultraviolet Near Infrared Infrared 1.1 mm 0.7 mm 0.7 mm Transmitted Wavefront Distortion (at nm) Ultraviolet Near Infrared Infrared Surface Quality Beam Deviation Wavelength Range Maximum Temperature Outside Dimensions Round Square ~ λ/4 per inch ~ 5λ per inch ~ 5λ per inch scratch and dig 1 arc min 400 nm to > 2000 nm 200 C for single layer 1 to 200 mm 1 to 140 mm On ultraviolet VersaLight, the wire grid surface will be unprotected, fragile and cannot be touched. UV VersaLight is optimized for nm NIR VersaLight is optimized for nm IR VersaLight is optimized for nm Ordering Information Standard VersaLight Dimension AR Coating Part Number Square 0.5 x 0.5 in. UV VLS-050-UV NIR IR VLS-050-NIR VLS-050-IR 1.0 x 1.0 in. UV VLS-100-UV NIR IR VLS-100-NIR VLS-100-IR 2.0 x 2.0 in. UV VLS-200-UV Round NIR IR VLS-200-NIR VLS-200-IR 0.5 in. diameter UV VLR-050-UV NIR IR VLR-050-NIR VLR-050-IR 1.0 in. diameter UV VLR-100-UV NIR IR VLR-100-NIR VLR-100-IR 2.0 in. diameter UV VLR-200-UV NIR IR VLR-200-NIR VLR-200-IR Call for information on even higher contrast, doubled assemblies. Custom sizes are available. Please contact your Meadowlark Optics sales engineer for assistance (303) mlo@meadowlark.com

13 Laser Line Beamsplitting Polarizers Key Benefits High Contrast Low reflectance High damage threshold Low transmitted wavefront distortion Meadowlark Optics right angle prisms are matched in pairs to produce high quality laser line beamsplitting polarizers with superior wavefront quality in both transmission and reflection. The hypotenuse face of one prism is coated with a multilayer dielectric beamsplitting coating optimized for laser performance. Two prisms are cemented together, protecting the critical coating from performance-degrading environmental factors. Each cube separates an unpolarized incident beam into two orthogonal, linearly polarized components with negligible absorption. Following the principle of pile-of-plates polarizers, p polarized light is transmitted while s polarization is reflected. Polarizers Retarders Mounting Hardware Devices Fig Typical performance of a Laser Line Beamsplitting Polarizer Fig Beamsplitting polarizers provide two orthogonally polarized beams, conveniently separated by 90 mlo@meadowlark.com (303)

14 Laser Line Beamsplitting Polarizers Polarizers PROBLEM How can I find precisely the polarization axis of a polarizer? Retarders SOLUTION The polarization direction is marked on all mounted and unmounted polarizers we sell. For a more precise determination, use a laser line beamsplitting polarizer. The transmitted linear polarization direction lies precisely in the plane defined by the incident and reflected laser beams. Mounting Hardware Devices Fig Beamsplitting polarizers provide two orthogonally polarized beams, conveniently separated by 90 Specifications Material Transmitted Wavefront Distortion (at nm) Contrast Ratio Transmitted Reflected Efficiency p-polarized light s-polarized light Clear Aperture Reflectance (per surface) Surface Quality Beam Deviation Transmitted Reflected BK 7 Grade A, fine annealed λ/5 for p-polarized beam 500:1 20:1 95% transmitted 99% reflected Central 80% diameter 0.25% at normal incidence scratch and dig 3 arc min 6 arc min Acceptance Angle ± 2 Standard Wavelengths: 532, 632.8, 670, 780, 850, 1064 and 1550 nm Dimensional Tolerance ± in. Temperature Range -40 C to +100 C Recommended Safe Operating Limit 500 W/cm 2, CW 300 mj/cm 2, 10 ns, visible 200 mj/cm 2, 10 ns, 1064 nm Ordering Information Dimensions A = B = C Part Number 0.50 BP λ 1.00 BP λ Please substitute your wavelength in nanometers for λ. Custom sizes and wavelengths, over nm are available. Call us for pricing on nonstandard wavelengths or sizes (303) mlo@meadowlark.com

15 Broadband Beamsplitting Polarizers Key Benefits High contrast Low reflectance Broad spectral range High damage threshold For applications involving broadband or tunable wavelength sources, Meadowlark Optics presents a full line of Broadband Beamsplitting Polarizers covering the visible to near infrared region. These cubes offer increased utility for a range of polarization needs. As with the Laser Line Beamsplitting Polarizers, two usable polarization forms result, conveniently separated by 90. For unpolarized input, incident light will be equally split, 50% transmitted and reflected. Varying the input polarization axis will change the split ratio. Polarizers Retarders Mounting Hardware Fig Design Performance of Visible Broadband Beamsplitting Polarizer Fig Design Performance of IR1 Broadband Beamsplitting Polarizer Devices Fig Design Performance of IR1 Broadband Beamsplitting Polarizer Fig Design Performance of IR3 Broadband Beamsplitting Polarizer mlo@meadowlark.com (303)

16 Broadband Beamsplitting Polarizers Polarizers The basic construction of this polarizer line is similar to the Laser Line Beamsplitting Polarizers previously described. Our choice of high-index glass for these polarizers aids in providing such broad usable wavelength ranges. However, these broadband designs require wellcollimated input and accurate angular alignment for optimum performance. All four entrance and exit faces are antireflection coated to minimize losses. Retarders Mounting Hardware Devices Specifications Material SF 2 Transmitted Wavefront Distortion (at nm) Contrast Ratio Transmitted Reflected λ/5 for p-polarized beam 500:1 20:1 Efficiency (average over wavelength range) p-polarized light s-polarized light Clear Aperture Reflectance (per surface) Surface Quality Beam Deviation Transmitted Reflected Acceptance Angle ± 2 Wavelength Ranges Visible Near IR1 Near IR2 Near IR3 Dimensional Tolerance Temperature Range Recommended Safe Operating Limit 95% transmitted 98% reflected Central 80% diameter 0.5% average at normal incidence scratch and dig 3 arc min 6 arc min nm nm nm nm ± in. -40 C to +100 C 500 W/cm 2, CW 300 mj/cm 2, 10 ns, visible 200 mj/cm 2, 10 ns, 1064 nm Ordering Information Dimensions A = B = C Visible ( nm) Part Number 0.50 BB VIS 1.00 BB VIS Near IR1 ( nm) 0.50 BB IR BB IR1 Near IR2 ( nm) 0.50 BB IR BB IR2 Near IR3 ( nm) 0.50 BB IR BB IR3 Custom sizes are available. Please contact our Sales Department (303) mlo@meadowlark.com

17 NEW UV Optics Key Benefits Wide range of UV Polarizers/Retarders Meadowlark quality Standard and Custom Options Available Meadowlark Optics is pleased to offer several polarizer and retarder options that work in the ultraviolet region of the light spectrum. Collected on this page are some of our offerings, both standard and custom. If you require any ultraviolet polarization optics, please contact your Meadowlark Optics sales engineer for assistance Polarizers Currently, Meadowlark Optics has several standard and custom polarizers that work in the ultraviolet region. Our Precision Linear Polarizer (see page 6) is our most economical offering and works well for low power applications with wavelengths between nm. Our Ultra High Contrast Polarizer (see page 9) allows the user to obtain contrast ratios in excess of 10,000,000:1 and is optimized for wavelengths between nm. A custom option with higher transmission and slightly lower contraast ratio is also available. Ultraviolet VersaLight (see page 11) works below 300 nm, and can be used as both a reflective and transmissive polarizer. It has a wide acceptance angle and comes in a wide range of shapes and sizes. While it comes standard with no coatings, Meadowlark Optics can apply either broadband antireflection coating opposite the wire grid, over the Ultraviolet region or a V-coat for a specific wavelength. Uncoated Glan - Thompson Polarizers (see page 18) also work down to 320 nm and give excellent contrast ratios over a broad wavelength range. By using ultraviolet transmitting optical cement, Meadowlark Optics can go deeper into the ultraviolet region. Meadowlark Optics can manufacture all type of calcite polarizers to work in the ultraviolet region. Also, Meadowlark Optics can produce custom Laser Line Beamsplitting Polarizers. Manufactured out of UV Grade Fused Silica, these polarizers are made for common wavlengths in the ultraviolet region. Finally, Alpha - Barium Borate is another ultraviolet polarizer option that Meadowlark Opitcs is currently pursuing. Please contact your Meadowlark Optics sales engineer for assistance. Retarders Meadowlark Optics recently added Compound Zero Order Quartz Retarders to our standard product offering (see page 29). These are made out of two multiple order quartz retarders with their optic axis directions being perpendicular to each other. Specific ultraviolet wavelengths are available. Quartz retarders are excellent for applications that require consistent performance over thermal variations. We also manufacture Multiple Order Quartz Retarders for various wavelengths in the ultraviolet region. By using precision polishing techniques, we can provide excellent transmission, surface and transmitted wavefront quality. For your achromatic retarder requirements, we recommend the Bi-Crystalline Achromatic Retarder (see page 38). These are manufactured out of crystalline quartz and magnesium fluoride. The standard ultraviolet version works to around 400 nm. Custom designs that work deeper into the ultraviolet region are available. We also manufacture Fresnel Rhombs that work over broad wavelength ranges, down to 250 nm. Based upon the principles of Total Internal Reflection, each reflection adds one eighth wave of retardance. Fresnel Rhombs come in quarter and half wave versions. Please contact your Meadowlark Optics sales engineer for assistance or a custom quote. Finally, in response to you, the customer, we are investigating the manufacturing of Devices for use in the ultraviolet region. Please visit our website, com or contact your Meadowlark Optics sales engineer for the latest information and assistance on this or any polarization requirements you may have in the ultraviolet region. Fig Ultra-High Contrast UV Polarizer has excellent contrast over 350 to 410 nm Fig Uncoated, air-spaced Glan-Laser Calcite Polarizers can be used from 250 to 2300 nm Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

18 Glan-Thompson Polarizers Polarizers Key Benefits Broad spectral range Excellent extinction ratio Retarders Mounting Hardware Calcite is a naturally occurring birefringent crystal. By precisely controlling internal prism angles in our calcite polarizers, a very efficient linear polarizer is produced. Meadowlark Optics offers Glan-Thompson Polarizers, intended for precision optical instrumentation and low power laser applications. Key advantages of Glan-Thompson Polarizers include excellent extinction ratio performance and a broad spectral range. Our Glan-Thompson Polarizers are supplied in a black anodized cylindrical housing for easy mounting. Although raw calcite material transmits down to 215 nm, the cement interface limits ultraviolet transmission. For this reason, we recommend Glan- Thompson Polarizers for use over nm. Three antireflection coating options cover the visible to near infrared range. Uncoated Glan-Thompson Polarizers are also available. Devices Fig Glan-Thompson Polarizer construction Ordering Information Clear Aperture (mm) Wavelength Range (nm) AR Coating Part Number None GTP M MgF 2 GTP M MgF 2 GTP M MgF 2 GTP M None GTP M MgF 2 GTP M MgF 2 GTP M MgF 2 GTP M Specifications Material Grade A Optical Calcite Extinction Ratio 10,000:1 over central 2/3 of clear aperture Reflectance (per surface, at normal incidence) Uncoated Single layer MgF 2 ~ 4.5% ~ 1.5% Beam Deviation ± 3 arc min Acceptance Angle ± 5 Wavelength Range nm Recommended Safe Operating Limit W/cm 2 CW None GTP M MgF 2 GTP M MgF 2 GTP M MgF 2 GTP M (303) mlo@meadowlark.com

19 Optical Isolation with Circular Polarizers Fig Dichroic Circular Polarizer construction Key Benefits Reduce back reflection Beam separation Combines polarizer and retarder in one component Circular Polarizers transmit either left-circular polarized light or right-circular polarized light for an input beam of any polarization state. When circularly polarized light is reflected, its propagation direction reverses, changing left-circular polarization to rightcircular polarization and vice-versa. Therefore the same polarizer that produces circular polarization of the incident beam will block the return beam. Achievement of optical isolation using the circular polarizers described in this catalog requires that the reflection be specular and that no significant depolar ization or polarization modification occur in any intervening medium between the reflector and optical isolator. We offer circular polarizers in two basic designs, each for use in air: Dichroic Polarizer/Zero-Order Retarder Beamsplitting Polarizer/Zero-Order Retarder Both designs take advantage of the handedness change of a circularly polarized beam upon reflection. Again, by changing the handedness of the circularly polarized beam, back reflections are blocked by the polarizer. The degree of this blocking is commonly used to evaluate circular polarizer performance. Termed isolation, it can be considered similar to the extinction ratio specification of a linear polarizer. Isolation represents the percentage of an incident beam which is blocked on its second pass through the circular polarizer. High isolation implies less light will be returned to the source. A more detailed description of the characteristics of circularly polarized light is provided in Polarized Light in Optics and Spectroscopy, page 5. Polarizers Retarders Mounting Hardware Devices Fig Optical isolation using a circular polarizer Custom sizes are available. Please contact our Sales Department. mlo@meadowlark.com (303)

20 Dichroic Circular Polarizers Polarizers Key Benefits High isolation Large diameters available Low transmitted wavefront distortion Retarders Mounting Hardware Devices Specifications Polarizer Material Retarder Material Substrate Material Dichroic Polymer Birefringent Polymer BK 7 Grade A, fine annealed Standard Wavelengths 532, 632.8, 670, 780, 850, 1064 and 1550 nm Isolation >99.8% Transmitted Wavefront Distortion (at nm) Visible Near Infrared Surface Quality Beam Deviation Visible Near Infrared Reflectance (per surface) Diameter Tolerance Mounted Unmounted Temperature Range Recommended Safe Operating Limit λ/5 λ/ scratch and dig 1 arc min 2 arc min 0.5% at normal incidence ±0.005 in. +0/ in. -20 C to +50 C 1 W/cm 2, CW Prolonged exposure to strong ultraviolet radiation may damage these polarizers. Meadowlark Optics Dichroic Circular Polarizers consist of a dichroic linear polarizer and true zero-order quarterwave retarder. Accurately aligning the retarder fast axis at 45 to the linear polarization direction ensures optimum performance. True zero-order retarders (page 30-31) are used in the assembly of our Dichroic Circular Polarizers. Tight retardance tolerances also contribute to the final performance. Once aligned, both polarizer and retarder materials are laminated between high quality optical flats, providing less than λ/5 transmitted wavefront distortion. Anti reflection coated windows ensure surface reflection losses are minimized. Achievement of the desired polarization effect requires proper orientation of your Dichroic Circular Polarizer. Be sure to position the indicator marking in the direction of beam propagation. For maximum transmission, rotate the circular polarizer to align a linearly polarized input beam polarization direction parallel to the marks on the housing. Our standard Dichroic Circular Polarizers are designed for single wavelength applications. Achromatic versions are also available on a custom basis. Please call for application assistance. Ordering Information Diameter Clear Aperture Mounted Thickness Part Number CPM λ CPM λ CPM λ Diameter Clear Aperture Unmounted Thickness Part Number CP λ CP λ Meadowlark Optics standard Dichroic Circular Polarizers provide left-hand circular output. Please call to request a quote for righthand circular output. Append a -RH to your part number for righthand circular output (303) mlo@meadowlark.com

21 Beam Separators Fig Beam Separator function Key Benefits High isolation Large diameters available Low transmitted wavefront distortion Meadowlark Optics Beam Separators are specially designed for laser line applications. Assembly consists of a true zero-order quarter-wave retarder (page 30-31) oriented with its fast axis at 45 to the transmission axis of a Laser Line Beamsplitting Polarizer (page 13-14). The transmitted beam is circularly polarized, regardless of the input beam polarization state. Our true zero-order Precision Retarders are one quarter-wave within ± λ/350 waves. Aligning the fast axis to within 1 ensures greater than 99.8% source isolation from specular back reflections. Specifications Material Transmitted Wavefront Distortion (at nm) Clear Aperture Reflectance (per surface) Surface Quality Beam Deviation BK 7 Grade A, fine annealed λ/5 Acceptance Angle ± 2 Central 80% diameter 0.5% at normal incidence scratch and dig 3 arc min Standard Wavelengths 532, 632.8, 670, 780, 850, 1064 and 1550 nm Dimensional Tolerance ±0.020 in. Temperature Range -20 C to +50 C Recommended Safe Operating Limit 500 W/cm 2, CW 300 mj/cm 2, 10 ns, visible 200 mj/cm 2, 10 ns, 1064 nm Polarizers Retarders Mounting Hardware Devices Ordering Information Cube Dimensions Clear Aperture Part Number BS λ BS λ Please substitute your wavelength in nanometers for λ. Custom sizes are available. Custom wavelengths over nm are available. Please contact our Sales Department to obtain a custom quote. mlo@meadowlark.com (303)

22 Polarizer Selection Chart Polarizers Retarders Mounting Hardware Devices Linear Beamsplitting VersaLight 11 broad spectral performance specularly reflective operation high power handling capability visible and near infrared versions up to 170 mm apertures available Laser Line 13 high contrast low reflectance high damage threshold Broadband 15 high contrast high damage threshold broad spectral performance Circular Dichroic Circular 20 high isolation large diameters available achromatic versions for broadband performance Beam Separator 21 high isolation excellent wavefront quality robust opto-mechanical design Wavelength Range Polarizer Type Page Product Features Precision Dichroic 6 custom shapes and large apertures available ultraviolet, visible, near infrared versions most economical linear polarizer choice limited power handling capability High Contrast 8 high contrast high transmission wavelength-specific design Ultra-High Contrast 9 broad spectral performance high temperature resistance highest available contrast ratio excellent ultraviolet product option Glan-Thompson 18 excellent extinction ratio broad spectral performance multilayer BBAR coatings also available standard products custom options 22 (303) mlo@meadowlark.com

23 Polarizer Selection Chart Linear Reflectance (maximum per surface) UV: ~4.25% VIS: 0.50% NIR: 0.50% Beam Deviation (maximum) UV: 2 arc min VIS: 1 arc min NIR: 2 arc min Transmitted Wavefront Distortion (maximum at mn) UV: λ/2 VIS: λ/5 NIR: λ/2 Acceptance Angle ± 10 Clear Aperture (diameter) 0.40, 0.70, 0.80, 1.20 in. 0.50% 3 arc min λ/4 ± , 0.70 in. ~4% (uncoated) ~1.50% (coated) ~4.50% (uncoated) Beamsplitting 1.50% 5 arc min 1λ per 10mm diameter ± , 0.70, 0.80 in. 3 arc min λ ± 5 5, 8, 10 mm 1 arc min UV: λ/4 per inch NIR: 5λ per inch IR: 5λ per inch ± , 0.80 in. Polarizers Retarders Mounting Hardware 0.25% 0.50% Trans:3 arc min Ref: 6 arc min λ/5 ± , 0.80 in. Trans:3 arc min Ref: 6 arc min λ/5 ± , 0.80 in. Devices Circular 0.50% VIS: 1 arc min NIR: 2 arc min VIS: λ/5 NIR: λ/2 ± , 0.70, 0.80, 1.20 in. 0.50% 3 arc min λ/5 ± , 0.80 in. Polarizer and Retarder sets available, see page 42. mlo@meadowlark.com (303)

24 Polarizers Retarders Devices Mounting Hardware Retarder Principles Retarders are used in applications where control or analysis of polarization states is required. Our retarder products include innovative polymer and liquid crystal materials as well as commonly used quartz. Other crystalline materials such as magnesium fluoride are also available upon request. Please call for a custom quote. A retarder (or waveplate) is an optical device that resolves a light wave into two orthogonal linear polarization components and produces a phase shift between them. The resulting light wave is generally of a different polarization form. Ideally, retarders do not polarize, nor do they induce an intensity change in the light beam, they simply change its polarization form. All standard catalog Meadowlark Optics retarders are made from birefringent, uniaxial materials having two different refractive indices the extraordinary index ne and the ordinary index no. The difference between the two indices defines the material birefringence. Light traveling through a retarder has a velocity v dependent upon its polarization direction given by v = c/n where c is the speed of light in a vacuum and n is the refractive index parallel to that polarization direction. By definition, ne > no for a positive uniaxial material. For a positive uniaxial material, the extraordinary axis is referred to as the slow axis, while the ordinary axis is referred to as the fast axis. Light polarized parallel to the fast axis travels at a higher velocity than light parallel to the orthogonal slow axis. In figure 2-1, a plane polarized light wave incident on a birefringent material is vectorially decomposed into two orthogonal components vibrating along the fast and slow axes. Plane polarized light is oriented at 45 relative to the fast axis of the retarder. The orthogonal polarization components travel through the material with different velocities (due to birefringence) and are phase shifted relative to each other producing a modified polarization state. The transmitted light leaves the retarder elliptically polarized. Retardance (in waves) is given by: d = bt/λ where: b = birefringence (ne - no) λ = wavelength of incident light (in nanometers) t = thickness of birefringent element (in nanometers) Retardance can also be expressed in units of length, the distance that one polarization component is delayed relative to the other. Retardance is then represented by: d, = dλ = bt where d, is the retardance (in nanometers). This equation illustrates that retardance is strongly dependent upon both incident wavelength and retarder thickness. All retarders suffer small retardance oscillations as a function of wavelength when a coherent light source is used. This etalon effect can be substantial, depending upon the thickness and surface reflections of the retarder. Retarder Types Birefringence is common in materials with anisotropic molecular order such as crystals (both solid and liquid) and oriented polymers. Crystalline retarders are often made of mica, calcite, or most commonly, quartz. Retarders can be multiple-order (having several waves of retardance), compound zero-order, or true zero-order. True zeroorder retarders are often preferred for the most demanding applications requiring retardance stability with wavelength, temperature and angle of incidence. A true zero-order retarder is thin and must have a low birefringence to be manufactured easily. A review of several retarder types is presented below. Quartz has a birefringence of ~ in the visible region. From the equations shown on the previous page, a true zeroorder quartz quarter waveplate for 550 nm operation is only 15 mm thick. Such a thin, fragile retarder presents handling difficulties in both fabrication and mounting. More commonly, multiple-order quartz retarders having a whole number of waves plus the desired fractional retardance (typically quarter- or half-wave) are offered. Precision polishing of the quartz substrate provides excellent surface and transmitted wavefront quality. However, multiple-order retarders can be extremely sensitive to incident angle, wavelength and temperature. As a rule of thumb, the retardance (in waves) for a 1 mm thick quartz retarder varies by about -0.5% per C. Quartz retarders are sometimes preferred for their durability and high transmission properties (303) mlo@meadowlark.com

25 Retarder Principles Fig. 2-1 Phase retardation A compound zero-order quartz retarder improves performance by combining two multiple-order quartz waveplates with the desired retardance difference. The fast axis of one plate is aligned with the slow axis of the other, cancelling the large retardance values and leaving only the desired fractional retardance difference (typically quarter- or half-wave). Thermal stability of compound zero-order quartz retarders is improved as temperature effects of the two retarders cancel. Mica, a natural mineral, is cleaved to precise thicknesses offering true zero-order retarders. However, cleaving is difficult over large apertures and does not offer the necessary tolerance or spatial uniformity required for most applications. Also, the long term supply of optical quality mica is uncertain. Polymer materials offer a lower birefringence than quartz and can therefore be made into true zero-order retarders of reasonable thickness. They are much less sensitive to incidence angle than either multiple- or compound zero-order quartz retarders. Birefringence dispersion (or variation with wavelength) varies with each polymer material. This factor is an important consideration when manufacturing polymer retarders. Meadowlark Optics protects the polymer material using a proprietary lamination process between optically flat windows. This assembly provides the transmitted wavefront quality necessary for precision optical applications. We precisely orent and layer several polymer sheets to make achromatic polymer retarders. These polymer stacks are then laminated between optical flats. Achromatic polymer retarders offer the versatility needed for broadband applications with demanding performance requirements. When a retarder must have the same retardance at two wavelengths that are separated by a span too large for an achromatic retarder, then a dual wavelength retarder may be the answer. Some versions of dual wavelength retarders can also provide different specified retardances at two different wavelengths. Liquid crystal retarders are electrically variable waveplates. Retardance is altered by applying a variable, low voltage waveform. These retarders are made by placing a thin liquid crystal layer between parallel windows spaced a few microns apart. Different liquid crystal materials range in birefringence from 0.05 to 0.26, enabling fabrication of thin, true zero-order retarders in the visible to near infrared region. Fresnel Rhombs use total internal reflection to create a phase shift between two orthogonal polarization components. Fresnel rhombs make excellent achromatic retarders. A more complete description of reflection retarders can be found in the references listed on page 5. Other tunable birefringent retarders use electro-optic crystals such as KD*P (potassium dideuterium phosphate). This material is used in Pockels cell retarders which operate at megahertz frequencies but require very high voltage for retardance control. Polarizers Retarders Mounting Hardware Devices Note that a compound zero-order quartz retarder does not provide improved field of view over a multiple-order retarder, only a true zero-order retarder does. mlo@meadowlark.com (303)

26 Polarization Control with Polymers Polarizers Retarders Devices Mounting Hardware Fig. 2-2 Polymer retarder assembly Fig. 2-3 Half-wave retarder performance versus incidence angle or Naturally-occurring crystalline materials (calcite, mica and quartz) have traditionally been the birefringent materials of choice for retarders. Today s applications require performance versatility beyond the limitations of those crystals. Meadowlark Optics specializes in the use of birefringent polymers and liquid crystals for polarization control in precision optical applications. These innovative materials offer a unique combination of high perfor mance and cost-effectiveness. Birefringent Polymers Our polymer retarder assembly consists of birefringent polymer material laminated between two precision polished, optically flat BK 7 windows. Antireflection coatings and index matching optical cement help to maximize transmission in the visible to near infrared region. This construction (shown in figure 2-2) ensures excellent transmitted wavefront quality, while minimizing beam deviation and surface reflection losses. Polymer retarders offer excellent angular field-of-view since they are true zero-order retarders. Figure 2-3 compares the change in retardance as a function of incidence angle for polymer and quartz retarders. A polymer retarder changes by less than 1% over a ± 10 incidence angle. Retardance accuracy with wavelength change is often a key concern. For example, an off-the-shelf diode laser has a center wavelength tolerance of ± 10 nm. Changes with temperature and drive conditions cause wavelength shifts which may alter performance. Meadowlark Optics polymer retarders maintain excellent retarder performance even with minor shifts in the source wavelength. We also produce achromatic retarders with excellent retar dance accuracy over a very broad wavelength range. Basic construction of achromatic retarders is the same as that for zero-order polymer retarders shown in figure 2-2. A comparison of different retarder types and their dependence on wavelength is shown in figure 2-4. The temperature sensitivity of laminated polymer retarders is about 0.04% per C, allowing operation over moderate temperature ranges without significantly degrading retardance accuracy. We can also thermally calibrate polymer retarders for specific operating temperatures. Large aperture quartz retarders are difficult to fabricate and become cost-prohibitive beyond two inches in diameter. Meadowlark Optics polymer retarders with large apertures can be fabricated for a reasonable price. Please call for a custom quotation. Custom sizes and retardances are available. Please contact your Meadowlark Optics sales engineer for assistance. 26 Fig. 2-4 Wavelength performance of common quarter-wave retarders (303) mlo@meadowlark.com

27 Polarization Manipulation with Retarders Fig. 2-5 Fig. 2-6 A quarter-wave retarder converts linearly polarized light to circularly polarized light, or vice versa A half-wave retarder rotates linearly polarized light by 2f. Micro Retarders PolyWave is a high birefringence polymer that enables ultra-thin retarders. Micro retarders passed rigid environmental testing with no change in retardance after many months of exposure to extreme conditions. Meadowlark Optics produces these retarders with dimensions less than 1 mm. The edges can be cut to allow the retarder to be used to within 15 mm of the edge. Due to the high birefringence of the PolyWave material, the total thickness of a 1550 nm half-wave retarder is only approximately 15 mm and a quarterwave retarder is approximately 8 mm thick. A retarder (or waveplate) alters the polarization of light in a manner that depends on the retardance and the angle between the retarder fast axis and the input plane of polarization. Examples of the most common waveplates follow. Quarter-Wave Retarder A quarter-wave retarder is used to convert light between circular and linear polarization forms. It changes linearly polarized light to circularly polarized light, when the angle between the input polarization and the retarder fast axis is 45. In figure 2-5, linearly polarized light is converted to righthand circular polarized light by the quarter-wave retarder. Upon exiting the quarter-wave retarder, light polarized parallel to the slow axis is retarded by 1/4 wave relative to light polarized along the fast axis. When recombined, the exit light is circularly polarized. Similarly, this retarder orientation will convert input righthand circular polarized light to vertical linearly polarized light for a reversed direction of travel. Optical Isolator A quarter-wave retarder is often combined with a linear polarizer to form an optical isolator, used to eliminate undesired reflections. A common application prevents unwanted reflected light from re-entering a laser cavity. Please see page 19 for a discussion of Optical Isolators. Half-Wave Retarder Half-wave retarders are sometimes called polarization rotators. A half-wave retarder flips the polarization direction of incoming light about the retarder fast axis. When the angle between the retarder fast axis and the input plane of polarization is 45, horizontal polarized light is converted to vertical. A half-wave retarder rotates a linear polarized input by twice the angle between the retarder fast axis and the input plane of polarization, as shown in figure 2-6. A half-wave retarder can also be used to change the handedness of a left-circular polarized beam to right-circular polarized, or vice versa. A half-wave retarder is also conveniently used to change the polarization direction where mechanical rotation of a large laser is impractical. Full-Wave Retarder Full-wave retarders are valuable components for eliminating unwanted polarization changes in an optical system. Many optical components, especially metal mirrors, alter the polarization state by introducing unwanted phase shifts. For example, a linearly polarized input beam becomes elliptically polarized upon reflecting off of a metal surface. Ellipticity can be accurately corrected by using a full-wave retarder and tilting it about either the fast or slow axis, to change its retardance slightly. Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

28 Polarizers Retarders Devices Mounting Hardware Polarization Analysis Example General Analysis Several methods exist for computing and analyzing the polarization states of an optical system. Two common ways of evaluating a system involve Mueller and Jones calculus where the polarization of a light beam and the effects of optical components on that polarization form are represented by simple means. In the general case, polarizing properties of an optical component are represented by a matrix. A vector describes the polarization form of the incident beam. Multiplying the matrix and vector, the resulting vector represents the polarization characteristics of light that has propagated through the component. The Stokes vector S describes light polarization as: S = I Q U V where: I = total light intensity, Q = intensity difference between horizontal and vertical linearly polarized components, U = intensity difference between linearly polarized components oriented at ± 45º and V = intensity difference between right and left circular components. The Mueller matrix M for a waveplate with retardance d (in degrees) and arbitrary fast axis orientation f (measured from the horizontal) is expressed as: C S 2 2 cos d M = 0 S 2 C 2 (1 - cos d) 0 S 2 sin d where: C 2 cos(2f) and S 2 sin(2f) The light output S, is calculated by: S, = MS. 0 S 2 C 2 (1 - cos d) S C 2 2 cos -C 2 sin d 0 -S 2 sin d C 2 sin d cos d An Example A simple analysis using a horizontal linearly polarized beam incident on a quarter wave retarder is shown below. Horizontal linearly polarized input light has a Stokes vector given by: The Mueller matrix representation for a quarter-wave retarder with its fast axis at 45º relative to the incoming polarization is: M = S = Multiplying the input Stokes vector S by the component Mueller matrix M results in: S, = This vector represents 100% right circular polarized light. The references shown on page 3 provide detailed and comprehensive descriptions of polarization theory. Also, our engineers are happy to help you with any questions you may have regarding your application (303) mlo@meadowlark.com

29 Compound Zero Order Quartz Retarders Specifications Retarder Material Retardance accuracy Above 300 nm Below 300 nm Transmitted Wavefront Distortion (at nm over central 8mm diameter) Reflectance (per surface) Crystal quartz, 2 pieces ± λ/300 ± λ/200 λ/ % at normal incidence Surface Quality scratch and dig Beam Deviation 10 arc sec Diameter Tolerance ± in. Common Wavelengths 266, 308, 355, 488, 514.5, 532 and 1064 nm Possible Wavelength Range 266 to 2500 nm Temperature Range -20 C to +80 C Recommended Safe Operating Limit 1 MW/cm 2 CW at 1064 nm 2 J/cm 2 for a 10 nsec pulse at 1064 nm Key Benefits Tolerates high temperature High CW laser damage threshold Tip tunable retardance Good UV transmission On a custom basis we provide air spaced compound zero order quartz retarders for special applications where higher damage threshold, or better UV transmission than normal is required. These retarders combine two multiple order quartz retarders with their optic axis directions perpendicular to one another. The net retardance of the pair is the difference in the retardance of these two retarders. The net retardance is as insensitive to temperature changes as a true zero order quartz retarder but is as sensitive to angle of incidence as a multiple order quartz retarder of the thickness of the sum of the two quartz pieces. Angle tuning of retardance permits adjustment for use at a wavelength nearby the design wavelength. NO STOCK ITEMS Available Only custom parts Ordering Information Diameter Clear Aperture Unmounted Example Thickness λ/4 Wave Part No. λ/2 Wave Part No ZQ-100-λ ZH-100-λ Polarizers Retarders Mounting Hardware Devices Fig. 2-7 Zero Order Quartz Retarder waveplate internal transmission mlo@meadowlark.com (303)

30 Polarizers Retarders Devices Mounting Hardware Precision Retarders Fig. 2-8 Quarter-wave Precision Retarder performance Key Benefits True zero-order retarders Excellent off-axis performance Unequaled measurement accuracy Less temperature dependence than quartz waveplates Lower cost than compound zero-order quartz waveplates Better angular acceptance than compound zero-order quartz waveplates Meadowlark Optics specializes in precision polymer retarders for the visible to near infrared region. Our Precision Retarders have the highest optical quality and tightest retardance tolerance of all polymer retarders. These true zero-order Precision Retarders consist of a birefringent polymer cemented between two precision polished, optically flat BK 7 windows. The retarder fast axis is conveniently marked for quick and easy reference. Precision Retarders are supplied with a broadband antireflection coating. Optical transmittance of a Precision Retarder is typically greater than 97%. The retardance d at a wavelength λ that is different from the center wavelength λc is given by: d dc(λc / λ) where dc is the retardance at λc. This relationship is very important when using sources which vary in wavelength from their nominal value. Figures 2-8 and 2-9 show the retardance behavior as a function of relative wavelength for a quarter- and half-wave retarder, respectively. The Mueller calculus described on page 24 can be used to calculate the transmitted polarization state based upon the retardance differences from the ideal case. Since polymer retarders are true zero-order devices, they offer the significant advantage of improved angular performance. You can expect less than 1% retardance change over ±10 incidence angle. Meadowlark Optics has developed precision ellipsometric techniques that can measure retardance to λ/1000. Our metrology for these measurements is the best in the industry. You can have absolute confidence that the calibration measurements supplied with your retarder are of the highest accuracy obtainable. Fig. 2-9 Half-wave Precision Retarder performance 30 (303) mlo@meadowlark.com

31 Precision Retarders PROBLEM My laser center wavelength varies by a few nanometers, but I need my retarder to be a nearly perfect quarter-wave of retardance for each wavelength in order to give maximum isolation. I ll go broke if I have to purchase 10 retarders spaced at 0.5 nm intervals. Is there another way? SOLUTION 0.5 nanometers exceeds even our tight tolerance on retardance! Try angle tuning your retarder. A 10 tilt can change the retardance by about 1.25 nm or waves of retardance at nm. Remember to tilt about the fast or slow axis of your retarder, likely at ±45 to your optical bench. See our Application Note about retarders at Another solution is to use a liquid crystal variable retarder, page 48. Specifications Retarder Material Substrate Material Birefringent Polymer BK 7 Grade A, fine annealed Standard Wavelengths 532, 632.8, 670, 780, 850, 1064 and 1550 nm Custom Wavelengths nm (specify) Standard Retardances λ/4 and λ/2 Retardance Accuracy λ/350 Transmitted Wavefront Distortion (at nm) Surface Quality Beam Deviation Reflectance (per surface) Diameter Tolerance Mounted Unmounted Thickness Tolerance Temperature Range Recommended Safe Operating Limit λ/ scratch and dig 1 arc min 0.5% at normal incidence ±0.005 in. +0/ in. ±0.020 in. 20 C to 50 C 500 W/cm 2, CW 600 mj/cm 2, 20 ns, visible 4 J/cm 2, 20 ns, 1064 nm Custom retardance values and sizes are available. Please call for a quote. PROBLEM I purchased a compound zero-order retarder for use in an imaging system where I need a good field of view. Do these really have the field of view of a true zero-order retarder? SOLUTION This is a common misconception. In fact, compound zero-order retarders are twice as bad as the multi-order retarders they are made from! If you need a good field of view, you must use a true zeroorder retarder. See our Application Note at Ordering Information Diameter Clear Aperture Mounted Thickness λ/4 Wave Part No. λ/2 Wave Part No NQM-050-λ NHM-050-λ NQM-100-λ NHM-100-λ NQM-200-λ NHM-200-λ Diameter Clear Aperture Unmounted Thickness λ/4 Wave Part No. λ/2 Wave Part No NQ-050-λ NH-050-λ NQ-100-λ NH-100-λ NQ-200-λ NH-200-λ Please specify your center wavelength λ in nanometers when ordering. Custom size retarders with improved transmitted wavefront distortion and/or beam deviation are available. Your requirements for custom shapes and sizes are also welcome. Please call for a quote. Meadowlark Optics one and two inch diameter retarders conveniently fit our Rotary Mounts. Please refer to page 43 for more information. Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

32 Polarizers Commercial Retarders Key Benefits Economical choice Excellent performance Retarders Commercial Retarders are our most affordable line of zero-order waveplates. They are suitable for applications where transmitted wavefront quality is less critical. These retarders use commercial quality glass windows and are designed as a low-cost alternative to our Precision Retarders described on pages Basic construction is the same as described on page 26. Both quarter- and half-wave retarders are available for popular wavelengths in the visible and near infrared regions. All Meadowlark Optics retarders have their fast axis conveniently marked. Devices Mounting Hardware Specifications Retarder Material Substrate Material Birefringent Polymer Commercial Quality Glass Standard Wavelengths 532, 632.8, 670, 780, 850, 1064 and 1550 nm Custom Wavelengths nm (specify) Standard Retardance λ/4 and λ/2 Retardance Accuracy λ/50 Transmitted Wavefront Distortion (at nm) Surface Quality Beam Deviation Reflection (per surface) Diameter Tolerance Mounted Unmounted Temperature Range Recommended Safe Operating Limit 3λ scratch and dig 3 arc min 0.5% at normal incidence ±0.005 in. +0/ in. -20 C to +50 C 500 W/cm 2, CW 600 mj/cm 2, 20 ns, visible 4 J/cm 2, 20 ns, 1064 nm Ordering Information Diameter Clear Aperture Mounted Thickness λ/4 Wave Part No. λ/2 Wave Part No RQM-050-λ RHM-050-λ RQM-100-λ RHM-100-λ RQM-200-λ RHM-200-λ Diameter Clear Aperture Unmounted Thickness λ/4 Wave Part No. λ/2 Wave Part No RQ-050-λ RH-050-λ RQ-100-λ RH-100-λ RQ-200-λ RH-200-λ Please specify your center wavelength λ in nanometers when ordering. Meadowlark Optics one and two inch retarders conveniently fit our Rotary Mounts. Please refer to page 43 for details. Custom sizes and retardance values are available (303) mlo@meadowlark.com

33 Wide Field Retarders Fig Half-wave Wide Field Retarder performance versus incidence angle Key Benefits Unmatched off-axis performance Standard and custom wavelength retarders Mounted and unmounted versions available Off-axis performance ideal for uncollimated light applications Meadowlark Optics now offers Wide Field Retarders, the latest innovation in near zero-order polymer retarder technology. At their design wavelength, Wide Field Retarders provide a consistent retardance value over a wide acceptance angle, out to 30 or more. Standard quarter- and half-wave designs are available for common wavelengths in the visible to near infrared region. Figure 2-10 shows the Wide Field Retarder performance as a function of incidence angle for the half-wave design. Quarterwave Wide Field Retarder performance is shown in figure Multilayer broadband antireflection (BBAR) coatings are included as standard. Note that BBAR coating performance varies with incidence angle; these coatings perform best at (or near) normal incidence. As with all Meadowlark Optics retarders, the fast axis is conveniently marked. Custom retardance values are available for wavelengths from nm. Please call for application assistance or to request a custom quotation. Polarizers Retarders Mounting Hardware Devices Fig Quarter-wave Wide Field Retarder performance versus incidence angle performance mlo@meadowlark.com (303)

34 Wide Field Retarders Polarizers Retarders Devices Mounting Hardware Specifications Retarder Material Substrate Material Birefringent Polymer BK 7 Grade A, fine annealed Standard Wavelengths 532, 632.8, 670,780,850, 1064 and 1550 nm Custom Wavelengths nm (specify) Standard Retardance λ/4 and λ/2 Retardance Accuracy λ/250 at normal incidence at the center of the part Retardance Change (at 30 tilt) Half-wave Quarter-wave Transmitted Wavefront Distortion (at nm) Surface Quality Beam Deviation Reflectance (per surface) At normal incidence At 30 incidence Diameter Tolerance Mounted Unmounted Temperature Range λ/100 λ/200 λ/ scratch and dig 1 arc min 0.5% 1.0% ±0.005 in. +0/ in. 0 C to 40 C Ordering Information Diameter Clear Aperture Mounted Thickness λ/4 Wave Part No. λ/2 Wave Part No WQM-050-λ WHM-050-λ WQM-100-λ WHM-100-λ WQM-200-λ WHM-200-λ Diameter Clear Aperture Unmounted Thickness λ/4 Wave Part No. λ/2 Wave Part No WFQ-050-λ WFH-050-λ WFQ-100-λ WFH-100-λ WFQ-150-λ WFH-150-λ Custom sizes and retardance values are available. Please contact your Meadowlark Optics sales engineer for a custom quote (303) mlo@meadowlark.com

35 NEW Dual Wavelength Retarders Fractional Wave Retardance Dual wavelength retarders can provide the same retardance at two wavelengths that are separated in wavelength by more than the span covered by an achromatic retarder. They can also provide different specified retardances at two different wavelengths. Traditionally these retarders have been made using crystal quartz and are multiorder retarders at both wavelengths. Our dual wavelength retarders use polymers instead. They are usually much lower order and consequently have a slower change in retardance with angle of incidence as shown in the figure. On average the order is about 20% of that for a comparable quartz dual wavelength retarder. Call for a quote on a custom coating on these normally uncoated retarders. The retardance tolerance is ±0.01waves at both wavelengths. Many custom combinations not listed in the catalog are available. Please call for a quote on your custom requirement. Standard unmounted sizes are 0.50 inches and 1.00 inches. Specifications Retarder Material Substrate Material Retardance Accuracy Transmitted Wavefront Distortion (at nm) Reflectance (per surface on uncoated retarders only) Diameter tolerance Beam Deviation Thickness Half inch diameter One inch diameter Temperature Range Quartz Polymer Angle of Incidence ( ) Fig Dual Wavelength Field of View Birefringent Polymer BK 7 Grade A, fine annealed λ/100 at both wavelengths λ/4 ~ 4% at normal incidence +0/ in. 1 arc min 0.14 in in. design dependant Custom anti-reflection coatings to provide less than 0.5% reflection at both wavelengths are available. Please call your Meadowlark Optics sales engineer for a quote. Key Benefits Low order Wide angular field Broad wavelength coverage QUESTION I have a need for a quarter (or half) wave retarder at two different wavelengths. Which do I order, the Precision Achromatic Retarder or the Dual Wavelength Retarder? Answer Dual wavelength retarders are primarily for use at two different wavelengths separated by 20% apart. If the wavelengths are both covered by one of our standard achromatic retarder wavelength ranges (please see the Specifications Box for Precision Achromatic Retarders on page 37), we recommend purchasing a Precision Achromatic Retarder. We can also do custom achromatic retarder wavelength ranges. Please contact your Meadowlark Optics sales engineer for assistance and a custom quote. If the wavelength difference between the two is greater than 30 to 35 % of the lower wavelength, then we recommend a Dual Wavelength Retarder. Please contact your Meadowlark Optics sales engineer for assistance so that we can design for you the required Dual Wavelength Retarder or if you need any help at all. QUESTION I need a Dual Wavelength Retarder with two non-standard retardances at two non-standard wavelengths. Can you help me? Answer: While not all retardance and wavelength combinations are available, we can manufacture tens of thousands of different combinations for our Dual Wavelength Retarders. Please contact your Meadowlark Optics sales engineer for assistance and a custom quote. Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

36 Dual Wavelength Retarders Polarizers Ordering Information First Retardance Second Retardance Available Combinations Diameter First Wavelength Second Wavelength Retarders Quarter wave Half wave Full wave Quarter wave Half wave Full wave nm nm nm 780 nm 976 nm nm 488 nm nm nm 780 nm 976 nm nm HOW TO ORDER DUAL WAVELENGTH RETARDERS Devices Mounting Hardware To order dual wavelength retarders, five pieces of information are required (with their symbols in brackets): 1. The First (or lower) wavelength [l 1 ] in nanometers 2. The Second (or higher) wavelength [l 2 ] in nanometers 3. The retardance at the first wavelength [R 1 ], where: a. Q = Quarter Wave Retardance b. H = Half Wave Retardance c. F = Full Wave Retardance 4. The retardance at the second wavelength [R 2 ] a. Q = Quarter Wave Retardance b. H = Half Wave Retardance c. F = Full Wave Retardance 5. The outside diameter, 0.50 in. or 1.00 in. [D] where a. 050 = 0.50 in. b. 100 = 1.00 in. The part number is then created by these five pieces of data and the letter D to start it off. Example 1: A dual wavelength retarder is requested with a full wave of retardance at 488 nm and a half wave of retardance at 976 nm. The outside diameter is 0.50 in. The part number is then: DFH /0976 Example 2: A dual wavelength retarder is requested with a quarter wave of retardance at nm and a quarter wave of retardance at nm. The outside diameter is 1.00 inches. The part number is then: DQQ /1064 Please note that the decimal is not included in the part number. D R 1 R 2 D l 1 /l 2 And we have 10,000 combinations! 36 (303) mlo@meadowlark.com

37 Precision Achromatic Retarders Meadowlark Optics Precision Achromatic Retarders are designed to provide a nearly constant retardance over a broad wavelength region. Standard quarter- and half-wave devices are available for common wavelength regions in the visible and near infrared. Fig Quarter-wave Achromatic Retarder performance Fig Half-wave Achromatic Retarder performance Our Precision Achromatic Retarders consist of carefully aligned birefringent polymer sheets laminated between precision polished, optically flat BK 7 windows. Assembly is quite similar to the assembly of our Precision Retarders. Optical transmittance varies slightly from the Precision Retarder because several polymer layers are used in each Achromatic Retarder. We provide retardance accurate to λ/100 for all wavelengths in the operating range. Achromatic retarders are an excellent choice for applications requiring broad wavelength use. Key Benefits Broad spectral range Superior field of view Specifications Retarder Material Substrate Material Standard Wavelength (nm) Birefringent Polymer Stack BK 7 Grade A, fine annealed Operating Range (nm) Retardance λ/4 and λ/2 Retardance Accuracy λ/100 Transmitted Wavefront Distortion (at nm) λ/4 Surface Quality scratch and dig Beam Deviation 1 arc min Reflectance (per surface) 0.5% at normal incidence Diameter Tolerance Mounted Unmounted Thickness Tolerance Temperature Range Recommended Safe Operating Limit Ordering Information Diameter Clear Aperture Mounted Thickness ±0.005 in. +0/ in. ±0.020 in. -20 C to +50 C 500 W/cm 2, CW 300 mj/cm 2, 10 ns, visible 500 mj/cm 2, 10 ns, 1064 nm λ/4 Wave Part No. λ/2 Wave Part No AQM-050-λ AHM-050-λ AQM-100-λ AHM-100-λ Diameter Clear Aperture Unmounted Thickness λ/4 Wave Part No. λ/2 Wave Part No AQ-050-λ AH-050-λ AQ-100-λ AH-100-λ Please include the standard wavelength λ in nanometers when ordering. Custom sizes or center wavelengths can be specified for your application. Custom sizes are available. Please contact your Meadowlark Optics sales engineer for assistance. Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

38 Polarizers Bi-Crystalline Achromatic Retarders Key Benefits High damage threshold Volume pricing Superior IR performance Retarders Devices Mounting Hardware Fig Quarter-Wave Bi-Crystalline Achromatic Retarder performance Meadowlark Optics is pleased to offer a selection of quarterand half-wave achromatic retarders that span the UV, visible, near IR and IR portions of the spectrum. Two multi-order crystalline retarders, one made of crystalline quartz and the other magnesium fluoride, are combined in a subtractive mode to give an effective zero-order waveplate. By a careful choice of waveplate thicknesses, retardance dispersion is balanced to give a nearly constant retardance (in waves) over a broad range of wavelengths. The useable wavelength range is defined to give a retardance value within λ/100 of the nominal value. Custom designs with larger achromatic ranges or deeper UV wavelengths are available on request. Bi-Crystalline Achromats are similar in achromatic performance to our polymer achromats in the visible, but they excel in the IR. They have higher power handling capability than our polymer achromats and can with stand higher storage temperatures. Their field of view is narrow compared to polymer achromats. Typically, they cannot be expected to meet their retardance accuracy for rays whose incidence angles exceed 1.5. If you must have the performance of a Bi-Crystalline Achromat and a large field of view, call us. We have a proprietary design that can be your polarization solution. Retardation (waves) Fig Half-Wave Bi-Crystalline Achromatic Retarder performance 38 (303) mlo@meadowlark.com

39 Bi-Crystalline Achromatic Retarders Specifications Materials Retardance λ/4 or λ/2 Retardance Accuracy Temperature Coefficient of Retardance Wavelength Range Ultraviolet Visible Near Infrared Infrared Transmitted Wavefront Distortion (at nm) Reflectance (per surface) Surface Quality Beam Deviation Temperature Storage Range Recommended Safe Operating Limit Quartz and Magnesium Fluoride λ/100 over wavelength range < λ/500 per C Quarter Wave Half Wave nm nm nm nm λ/ nm nm nm nm 0.5% at normal incidence scratch and dig 1 arc min -40 C to +75 C 2 J/cm 2, 10 ns, 1064 nm Ordering Information Diameter Clear Aperture Mounted λ/4 Wave Part No. λ/2 Wave Part No CQM-050 CHM-050 Unmounted CQ-050 CH-050 We offer standard Bi-Crystalline Achromatic Retarders to cover 4 regions of the spectrum (see graph): UV, VIS, NIR, IR. Please specify wavelength region when placing your order. Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

40 Retarder Selection Chart Polarizers Retarder Selection When selecting a retarder, key performance features must be considered. These features include wavelength dependence, temperature sensitivity, acceptance angle, response time and aperture size. Our Retarder Selection Chart provides an at-a-glance review of standard retarders. Meadowlark Optics is a leader in retarder metrology among commercial companies. Our proprietary measurement techniques provide you with extremely accurate calibration measurements for every retarder we ship. Meadowlark Optics engineers are happy to assist you in the process of selecting a retarder. Retarders Wavelength Range Retarder Type Page Product Features Precision 30 most popular retarder type large, custom clear apertures available insensitive to small wavelength variations Devices Mounting Hardware Commercial 32 most economical retarder choice insensitive to small wavelength variations Wide Field 33 unmatched on-axis performance ideal for uncollimated light applications standard and custom wavelength versions Dual Wavelength 35 low order wide angular field broad wavelength coverage Compound Zero Order Quartz 29 tolerates high temperature high CW laser damage threshold tip tunable retardance Precision Achromatic 37 industry-leading design excellent broadband operation custom wavelength ranges available Bi-Crystalline Achromatic 38 superior infrared performance high power handling capability excellent broadband operation optic axis independent of wavelength Variable 48 unmatched versatility electrically controlled retardance custom retardance ranges available standard products custom options 40 (303) mlo@meadowlark.com

41 Retarder Selection Chart Polymer retarders offer much better field of view than either multiple-order or compound zero-order quartz retarders (Figure 2-4, pg. 26). Large clear apertures are cost effective using polymer retarders. Polymer retarders are less sensitive to wavelength change than multiple-order quartz retarders (Figure 2-4, pg. 26). By design, our achromatic retarders offer much lower retardance variation with wavelength than any other birefringent retarder (Figure 2-4, pg. 26) Retardance Accuracy Reflectance (maximum per surface) Beam Deviation (maximum) Zero-order polymer retarders are lower in cost than compound zero-order quartz retarders. retarders offer real-time, continuous control of retardance with no moving parts. We offer polymer and liquid crystal retarders in nonstandard sizes and for custom wavelengths and retarder values. Multiple-order quartz retarders are preferred for high power laser applications and can be designed for dualwavelength operation. Transmitted Wavefront Distortion (maximum at mn) Acceptance Angle ± λ/ % 1 arc min λ/5 ± 10 ± λ/50 0.5% 3 arc min 3λ ± 10 ± λ/ % 1 arc min λ/2 ± 30 ± λ/100 ~ 4% 1 arc min λ/4 ± 5 Above 300 nm: ± λ/300 Below 300 nm: ± λ/200 Clear Aperture (diameter) 0.40, 0.70, 0.80, , 0.70, 0.80, , 0.70, 0.80, , 0.70, % 10 arc sec λ/4 ± , 0.80 Polarizers Retarders Mounting Hardware Devices ± λ/ % 1 arc min λ/4 ± , 0.70, 0.80 ± λ/ % 1 arc min λ/4 ± tunable with ± λ/500 resolution 0.5% 2 arc min λ/4 ± 2 to 10 (dependent upon applied voltage) 0.37, Polarizer and Retarder kits available, see page 42. mlo@meadowlark.com (303)

42 Polarizers NEW Polarizer/Retarder Sets Key Benefits Convenient box set Precise components Retarders Meadowlark Optics Polarizer/Retarder sets include either a VIS, NIR1 or NIR2 linear polarizer and several precision retarders as described on pages within the same wavelength range as the polarizer. By using different combinations, a variety of different polarization states can be accurately and reproducibly created. For example, a linear polarizer with a quarter-wave retarder at 45 degrees can be used to make circularly polarized light. The parts are 1" diameter, 0.7 clear aperture and are packaged in a protective wooden box. Each component is mounted in a black anodized aluminum ring. Ordering Information Devices Mounting Hardware For polarizer specifications please refer to page 7. For retarder specifications please refer to page 31. Fig A quarter-wave retarder converts linearly polarized light to circularly polarized light, or vice versa Item PRS1 sets include a polarizer and one retarder. VIS Polarizer/Retarder Set NIR1 Polarizer/Retarder Set NIR2 Polarizer/Retarder Set Part Number PRS1-VIS-λ PRS1-NIR1-λ PRS1-NIR2-λ PRS3 sets include a polarizer and three retarders. VIS Polarizer/Retarder Set PRS3-VIS-λ 1 / λ 2 / λ 3 NIR1 Polarizer/Retarder Set PRS3-NIR1-λ 1 / λ 2 / λ 3 NIR2 Polarizer/Retarder Set PRS3-NIR2-λ 1 / λ 2 / λ 3 PRS5 sets include a polarizer and five retarders. VIS Polarizer/Retarder Set PRS5-VIS-λ 1 / λ 2 / λ 3 / λ 4 / λ 5 NIR1 Polarizer/Retarder Set PRS5-NIR1-λ 1 / λ 2 / λ 3 / λ 4 / λ 5 NIR2 Polarizer/Retarder Set PRS5-NIR2-λ 1 / λ 2 / λ 3 / λ 4 / λ 5 Please specify your wavelength(s) λ in nanometers when ordering. Half wave and quarter wave retarders are available over the following regions: VIS: nm NIR1: nm NIR2: nm 42 (303) mlo@meadowlark.com

43 Rotary Mounts Key Benefits Holds standard size optics Ease of use Available now Meadowlark Optics Rotary Mounts provide fine angular adjustment often required in polarization control applications. A threaded retaining ring holds mounted optical components in place. Full 360 rotation is possible using the knurled edge. Angular position is indicated on the graduated scale, with 2 increments. Two precision bearings provide smooth rotation with zero back-lash. A threaded locking screw secures your component in position. Two versions are available, for either one or two inch diameter parts. A two inch mounting post is included. Mounting Post and Base Set Meadowlark Optics standard liquid crystal devices are mounted in a black anodized aluminum housing, tapped with an 8-32 hole. Our Mounting Post and Base Set is designed to mate the liquid crystal housing with standard optical table and breadboard hole patterns. A knurled, threaded thumbscrew locks your optical component at the desired height. Simple and convenient angular adjustment is also provided. Polarizers Retarders Mounting Hardware Fig. 3-1 Rotary Mount dimensions Specifications Mounting Post Dimensions Diameter Length Base Dimensions Height Hole Pattern ±0.004 in ±0.010 in in in. through holes on 2.00 in. bolt circle diameter Liquid Drive Crystal Electronics Devices Ordering Information - Mounting Post and Base Item Part Number Mounting Post and Base Set Ordering Information - ROTARY MOUNTS Inside Diameter Outside Diameter Thickness Height MPB-1 Part Number RM RM702 mlo@meadowlark.com (303)

44 Polarizers NEW Beamsplitter Cube Mounts Key Benefits Holds standard size optics Ease of use Meadowlark provides beamsplitter mounts which allows precision positioning of beamsplitting polarizers up to 32 mm in size. Retarders A B Max E C Mounting Hardware Devices Fig mm mount 3-axis stage (tip, tilt and rotation) Devices Fig. 3-4 B A Top View Specifications Dimensions (mm) 1/4-20 counterbored hole BCM-M40 prism axis A B C D E 8-32 Side View Max Prism Size Part Number mm BCM-M mm BCM-M10 D Fig mm mount 3-axis stage (tip, tilt and rotation) 3 counterbored clearance holes: M2 on 20 mm centers 3 holes: M2 on 20 mm spacing B A C 20 mm Max E D 12.5 mm 35 mm Top View Side View Fig. 3-5 BCM-M25 prism axis 44 (303) mlo@meadowlark.com

45 Polarization Control with s Variable Retarders are solid state, real-time, continuously tunable waveplates. Nematic liquid crystals are birefringent materials whose effective birefringence can be changed by varying an applied voltage. Meadowlark Optics Retarders are constructed using precision polished, optically flat fused silica windows spaced a few microns apart. The cavity is filled with nematic liquid crystal material and sealed. This assembly ensures excellent transmitted wavefront quality and low beam deviation required for many demanding applications. The long axis of the liquid crystal molecules defines the extraordinary (or slow) index. With no voltage present, the molecules lie parallel to the windows and maximum retardance is obtained. When voltage is applied across the liquid crystal layer, the molecules tip toward the direction of the applied electric field. As voltage increases, the effective birefringence decreases, causing a reduction in retardance. See Figure 4.6. Fig. 4-1 Voltage Retardance Output State V 2 d = l/2 2 < V < 4 l/4 < d < l/2 V 4 d = l/4 4 < V < 7 0 < d < l/4 V 7 d = 0 Output polarization forms for different retardance values of a compensated variable retarder with horizontal linearly polarized input Liquid crystal retarders can offer outstanding performance over large incidence angles. Material type, cavity thickness and especially operating voltage play a large role in determining the acceptable input angle. Phase control or modulation is possible for light linearly polarized 45 to the fast axis. Electrical control of the effective extraordinary index allows precision tuning of an optical phase delay in the propagating beam. Variable Retarders Meadowlark Optics Variable Retarders provide precise solid-state retardance tunability. These true zero-order devices are precision engineered, offering excellent performance in the visible to near infrared wavelength ranges. When combined with other optical components, our Variable Retarders produce electrically controllable attenuation, linear polarization rotation, or phase modulation. Continuous tuning of retarders over a broad wavelength range is required for many applications. This added versatility makes real-time polarization conversion possible with a single Liquid Crystal Variable Retarder and electronic controller. Figure 4-1 shows a variety of output polarization forms achieved with a single device. Pure phase modulation is accomplished by aligning the optic axis of the liquid crystal retarder parallel to a linearly polarized input beam. Variable attenuators with no mechanical rotation are configured by placing a Variable Retarder between crossed polarizers. Full 180 linear polarization rotation can easily be achieved by combining the Variable Retarder with a fixed quarter waveplate. Spatial Light Modulators consist of individually controllable pixels. These devices are used in a variety of intensity and/or phase control applications where spatial variation is required. Please refer to the Spatial Light Modulator section for details and specifications on these innovative products. Polarizers Retarders Mounting Hardware Devices Retardances greater than half-wave can be achieved by using high birefringent materials and/or increased liquid crystal layer thickness. Birefringence of liquid crystal materials decreases at longer wavelengths, requiring proper evaluation and design for optimum performance. Meadowlark Optics Variable Retarders are used throughout the visible and near infrared region. While these liquid crystal retarders are affected by temperature and wavelength changes, they can be calibrated to accommodate those differences. The resulting Variable Retarder is versatile across a considerable thermal environment and significant wavelength range. A Variable Retarder is the fundamental component used in the following devices and systems. Variable Attenuators and Rotators Variable Beamsplitters Spatial Light Modulators Non-Mechanical Shutters Beam Steerers Optical Compensators Polarimeters Tunable Filters NEW from Meadowlark Optics Swift Variable Retarders, see page 56 mlo@meadowlark.com (303)

46 Custom Capabilities Polarizers Retarders Mounting Hardware Devices Variable Retarders A basic building block of Meadowlark Optics line of liquid crystal products is the Variable Retarder (LCVR). Just one of these devices can replace an entire series of polymer and standard crystalline retarders. They are electronically adjustable from nearly zero waves (or less than with an optional compensator) to over half- wave in the order of 10 milliseconds. With our new Swift LC technology, the switching speeds are symmetric and approximately 150 microseconds. An advanced use of LCVRs is described in the application note Stokes Polarimetry Using Retarders, which is available on our website at While we typically list our standard products as the Liquid Crystal Variable Retarder, Attenuator and Polarization Rotator, we also have the ability to utilize s in other ways that are extremely useful. The Twisted Nematic Device (TN) provides our customers with potential for custom applications where a standard LCVR might not be appropriate. At Meadowlark Optics we never cease working on polarization solutions for our customers. We hope the information below will provide our customers with new ideas that will challenge us to create new, exciting solutions for polarization control. Twisted Nematic Cell One is often only interested in producing two orthogonal linear polarization states of an optical system, or, in the case of a digital optical switch, only two states are frequently required. If you desire to switch the polarization state between only two angles, for example 0 and 90, a twisted-nematic device is an excellent solution. A big advantage of the twisted nematic device over an LCVR is the simplicity of the driving scheme. High voltage (above ~10 V) gives 0 rotation and low voltage (below ~1 V) gives 90 rotation, so you need not concern yourself with exact voltages or tight tolerances. Also, the field of view is wide when compared to an LCVR because the cell is being used in a situation where the optical axis of the liquid crystal molecules is not at an arbitrary angle to the light but is either parallel or perpendicular to it. A twisted nematic liquid crystal cell is constructed in the same manner as a standard LCVR except the alignment of the liquid crystal molecules is twisted 90. As in an LCVR, high voltage (~10 V) aligns the molecules with the field and removes the birefringence and therefore does not affect the light. At low voltage, however, the twist does affect the light, causing rotation of the polarization. If the twist is gentle when compared to the wavelength of the light, the polarization will simply follow the twist of the liquid crystal molecules. Such a cell is said to be operating in the Mauguin limit and its rotation is quite achromatic. The polarization rotation angle is equal to the twist angle for all wavelengths, which are short enough for the twist to be viewed as sufficiently gentle. When this is not the case, the cell will no longer act as a pure rotator. The result of inputting linearly polarized light is no longer an output of rotated linearly polarized light, but rotated elliptically polarized light. However, for certain discrete wavelengths, depending on the birefringence of the liquid crystal and the thickness of the cell, the pure rotation characteristic is retained. This concept is illustrated in figure 4-2, which shows the transmission (normalized to 1), of a 90 twisted nematic cell between parallel polarizers to be a function of the variable, U = 2d(b/λ), where d is the thickness of the cell, b is the birefrin gence and λ is the wavelength. Where the curve first goes to zero is termed the first minimum and this position is typically used. The next highest transmission minimum is called the second minimum and so on. In this plot, moving along the horizontal axis can be viewed as increasing thickness or decreasing wavelength. One might ask, given the achromaticity of thicker cells why use the first minimum? The simple answer is speed. The switching speed of an LC is a strong function of the cell thickness; generally, speed drops quadratically with the thickness. Thus, while a cell operating at a particular wavelength in the first minimum condition might switch in 10 to 50 ms, one designed to operate achromatically (for example to transmit <1% between parallel polarizers) over the entire visible range can take several seconds to switch. NEW from Meadowlark Optics Swift Variable Retarders, see page (303) mlo@meadowlark.com

47 Custom Capabilities Transmission Fig Transmission of a twisted-nematic cell between parallel polarizers as a function of thickness and/or wavelength Figure 4-4 shows the high contrasts of several thousands to one, which can be achieved in practice with twisted nematic cells. The curve termed Normally Black Contrast was taken between parallel polarizers where low voltage gives a dark state and high voltage yields a bright state. The curve termed Normally White Contrast was taken between perpendicular polarizers where the dark state occurs at high voltage. Custom sizes are available. Please contact your Meadowlark Optics sales engineer for assistance Fig Liquid crystal cell thickness changes Polarizers Retarders Mounting Hardware Devices Specifications Contrast Ratio Liquid crystal design space Switching Speed Wavelength Range Retardances Extinction Ratio Clear Aperture 50 ms to several seconds 350 nm-2.2 microns (or phase delay) 0 to 10,000 nm. Up to 50,000:1 for linear polarized monochromatic light 1 mm to 100 mm Normally White Contrast Normally Black Contrast Fig. 4-4 Contrast ratio for a twisted nematic liquid crystal cell mlo@meadowlark.com (303)

48 Variable Retarders Polarizers Retarders Anisotropic nematic liquid crystal molecules form uniaxial birefringent layers in the liquid crystal cell. An essential feature of nematic material is that, on average, molecules are aligned with their long axes parallel, but with their centers randomly distributed as shown in figure 4-6(a). With no voltage applied, the liquid crystal molecules lie parallel to the glass substrates and maximum retardation is achieved. When voltage is applied, liquid crystal molecules begin to tip perpendicular to the fused silica windows as shown in figure 4-6(b). As voltage increases, molecules tip further causing a reduction in the effective birefringence and hence, retardance. Molecules at the surface, however, are unable to rotate freely because they are pinned at the alignment layer. This surface pinning causes a residual retardance of ~30 nm even at high voltage (20 volts). Mounting Hardware Devices T hese products all use nematic liquid crystal materials to electrically control polarization. Meadowlark Optics standard liquid crystal products provide tunable retardation by changing the effective birefringence of the material with applied voltage, thus altering the input polarized light to any chosen elliptical, linear or circular polarization. Our precision Variable Retarders require unique fabrication and assembly steps. We construct these retarders using optically flat fused silica windows coated with our transparent conductive Indium Tin Oxide (ITO). Our ITO coating is specially designed for maximum transmission from nm (see Figure 4.5). A thin dielectric layer is applied over the ITO and gently rubbed, to provide for liquid crystal molecular alignment. Two windows are then carefully aligned and spaced a few microns apart. The cavity is filled with birefringent nematic liquid crystal material. Electrical contacts are attached and the device is environmentally sealed. We carefully place the Variable Retarder in an anodized aluminum housing such that the fast and slow axes are both at 45 relative to a convenient mounting hole. Fig. 4-6 (a) Maximum Retardance (V = 0) Fused Silica ITO Alignment Layer Spacer (b) Minimum Retardance (V >> 0) LC Molecules LC Molecules tipped with applied voltage Variable Retarder construction showing molecular alignment (a) without and (b) with applied voltage Fig. 4-5 Typical transmission through an uncoated liquid crystal device We achieve zero (or any custom) retardance with a subtractive fixed polymer retarder, called a compensator, attached to the liquid crystal cell. Negative retardance values are sometimes preferred, for example, when converting between right- and left-circularly polarized states. Figure 4-8 illustrates retardance as a function of voltage for a typical Liquid Crystal Variable Retarder with and without an attached compensator. Placing a compensated Variable Retarder between two high extinction polarizers creates an excellent optical attenuator, with convenient electronic control. As with any anisotropic material, retardance is dependent upon thickness and birefringence. Liquid crystal material birefringence depends on operating wavelength, drive voltage and temperature. The overall retardance of a liquid crystal cell decreases with increasing temperature (approximately -0.4% per ºC) (303) mlo@meadowlark.com

49 Variable Retarders Fig.4-7 Temporal response of LC Variable Retarder The applied voltage is a 2 khz square wave. Excessive DC voltage will damage the liquid crystal a) b) Fig.4-8 Variable Retarder performance versus applied voltage at nm, 21 C. (a) without compensator and (b) with compensator Response Time Variable Retarder response time depends on several parameters, including layer thickness, viscosity, temperature, variations in drive voltage and surface treatment. Liquid crystal response time is proportional to the square of the layer thickness and therefore, the square of the total retardance. Response time also depends upon direction of the retardance change. If the retardance increases, response time is determined solely by mechanical relaxation of the molecules. If retardance decreases in value, response time is much faster due to the increased electric field across the liquid crystal layer. Typical response time for our standard visible Variable Retarder is shown in figure 4-7b. It takes about 5 ms to switch from one-half to zero waves (low to high voltage) and about 20 ms to switch from zero to one-half wave (high to low voltage). Response time improves by using custom materials with high birefringence and a thinner liquid crystal layer. At higher temperature, material viscosity decreases, also contributing to a faster response. For speed critical applications, see page 56 for Swift LC devices. Another technique involves the Transient Nematic Effect (TNE) to improve response times. With this drive method, a high voltage spike is applied to accelerate the molecular alignment parallel to the applied field. Voltage is then reduced to achieve the desired retardance. When switching from low to high retardance all voltage is momentarily removed to allow the liquid crystal molecules to undergo natural relaxation. Response time achieved with the transient nematic effect is also shown in figure 4-7c. Our Four Channel Digital Interface described on pages conveniently provides the necessary TNE voltage profiles. Our standard Variable Retarders provide a minimum retardance range of ~30 nm to at least half-wave at the specified wavelength. With an attached compensator, retardance is guaranteed to range from zero to at least half-wave at the specified wavelength. Custom retardance ranges (up to a few waves) and custom compensators are available. Contact our Sales Department to discuss your requirements. Each Variable Retarder is supplied with retardance versus voltage performance data for your specified wavelength. A coaxial cable with mating connector is provided for easy attachment to one of our electronic controllers. QUESTION The temporal response of a liquid-crystal device seems very complicated. Where can I find some clarification? ANSWER See our Application Note on tempo ral response of liquid crystal devices at Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

50 Polarizers Retarders Variable Retarders Liquid crystal devices should be electrically driven with an AC waveform with no DC component to prevent ionic buildup which can damage the liquid crystal layer. We require a 2 khz square wave of adjustable amplitude for controlling our Variable Retarders (LCVR). Our Basic Controller and Four Channel Interface described on pages ensure these drive requirements are met. A temperature sensing and control option can be added to our LCVRs for accurate controlling of the operating temperature. The sensor is attached directly to the LCVR substrate, outside its clear aperture. Without this option, retardance decreases by approximately 0.2% to 0.3% per C increase in temperature. Key Benefits Computer control capability Temperature control options Usable from 450 to 1800 nm Precision non-mechanical retardation control Mounting Hardware Devices Fig. 4-9 Specifications Retarder Material Substrate Material Wavelength Range Retardance Range Without compensator With compensator Transmitted Wavefront Distortion (at nm) Surface Quality Beam Deviation Model LVR-100 dimensions All dimensions in inches Reflectance (per surface) Diameter Tolerance Nematic liquid crystal Optical quality synthetic fused silica nm (specify) ~30 nm to λ/2 0 to λ/2 custom ranges are available λ/ scratch and dig 2 arc min 0.5% at normal incidence ± in. Temperature Range 0 C to 50 C Recommended Safe Operating Limit 500 W/cm 2, CW 300 mj/cm 2, 10 ns, visible Fig Models LVR-200 and LVR-300 dimensions All dimensions in inches Ordering Information Diameter, D Clear Aperture, CA Thickness t Without Attached Compensator (30 nm to λ/2) Part Number LVR LVR LVR With Attached Compensator (0 nm to λ/2) LRC LRC LRC We offer standard liquid crystal variable retarders to cover four spectral regions: VIS: nm IR 1: nm IR 2: nm IR 3: nm Please specify spectral region when placing your order. For temperature control option, append-tsc to part number (303) mlo@meadowlark.com

51 Variable Attenuators Unpolarized Input Entrance Polarizer 45 f Compensated Variable Retarder Exit Polarizer Linear Polarized Output Fig Standard Variable Attenuator design uses crossed linear polarizers s Key Benefits High contrast ratio Computer control capability Continuous control of light intensity Meadowlark Optics (LC) Variable Attenuator offers real-time, continuous control of light intensity. Our attenuator consists of an LC Variable Retarder (with attached compensator) operating between crossed linear polarizers. With crossed polarizers, light transmission is maximized by applying the correct voltage to achieve half-wave retardance from the LC cell as shown in figure Half-wave operation rotates the incoming polarization direction by 90, so that light is passed by the second polarizer. Minimum transmission is obtained with the retarder operating at zero (or a whole number of) waves. Transmission decreases as the applied AC voltage amplitude increases (half- to zero-waves retardance). The relationship between transmittance T and retardance θ (in degrees) for crossed polarizer configuration is given by: T(θ) = 1/2 [1 - cos(θ)] Tmax where Tmax is the maximum transmittance when retardance is exactly one-half wave (or 180º). Figure 4-12 shows transmittance as a function of applied voltage. Maximum transmission is dependent upon properties of the LC Variable Retarder as well as the polarizers used in your system. Figure 4-13 shows the transmission of an LC Variable Attenuator optimized for use at 550 nm with crossed polarizers. An unpolarized light source is used for illumination. Contrast ratio is defined as the maximum transmission (obtained with the LC cell at half-wave operation) divided by the minimum transmission (obtained with the LC cell at zero waves). Values exceeding 1000:1 (see figure 4-14) can be obtained for a single wavelength by optimizing the applied voltage levels for minimum and maximum transmission. We guarantee a minimum contrast ratio of 500:1 at your specified wavelength. Polarizers Retarders Mounting Hardware Devices Fig Normalized transmittance of Variable Attenuator with crossed linear polarizers at a single wavelength Fig Unpolarized Transmittance as a function of wavelength for LC Variable Attenuator, optimized for 550 nm, with polarizers and unpolarized input mlo@meadowlark.com (303)

52 Variable Attenuators Polarizers Retarders A Variable Attenuator can be configured with high efficiency calcite or beamsplitting polarizers to maximize light transmittance and increase damage threshold. With a linearly polarized input beam and a calcite polarizer, transmittance values exceed 90% at most wavelengths. Very high contrast ratios, in excess of 5000:1, can be achieved with custom double attenuators. In this design, two Variable Retarders are combined with three polarizers. Custom devices for near infrared applications, utilizing appropriate dichroic polarizers, can also be manufactured. Please see the section on Polarizers for a selection of available polarizers. Our Basic Controller and Four Channel Interface described on pages offer the precision waveforms necessary to obtain accurate and repeatable intensity control for your application. Specifications Retarder Material Polarizer Material Substrate Material Wavelength Range Visible Near Infared 1 Near Infared 2 Contrast Ratio Transmitted Wavefront Distortion (at nm) Surface Quality Nematic liquid crystal with Birefringent polymer Dichroic polymer Optical quality synthetic fused silica nm nm nm 500:1 at single wavelength λ/4 (each component) scratch and dig Beam Deviation 2 arc min Mounting Hardware 10,000 Reflectance (per surface) Diameter Tolerance Temperature Range Recommended Safe Operating Limit 0.5% at normal incidence ±0.005 in. 0 C to +50 C 1 W/cm 2, CW (with dichroic polarizers) Devices Contrast Ratio 1, Ordering Information Diameter, D Clear Aperture,CA Thickness t Part Number LVA λ LVA λ LVA λ Please specify operating wavelength λ in nanometers when placing your order. Custom sizes are available. Fig Typical Contrast Ratio of a Variable Attenuator optimized at 550 nm 52 (303) mlo@meadowlark.com

53 Polarization Rotators Our Polarization Rotator continuously rotates the polarization direction of a monochromatic, linearly polarized input beam. Our design consists of a Variable Retarder combined with a zero-order polymer quarter-wave retarder. The fast axis of the liquid crystal variable retarder is oriented at 45 to the slow axis of the quarter-wave retarder. Linearly polarized input must be parallel to the quarter-wave retarder slow axis. Polarization rotation is achieved by electrically controlling the retardance of the Variable Retarder, eliminating any mechanical motion. A quarter-wave retarder converts elliptical polarization formed by the Variable Retarder to linear polarization. The rotation angle is equal to one-half the retardance change from the Variable Retarder. Response time depends upon the desired amount of rotation. Small rotations have longer response times. Key Benefits High power capability High polarization purity Computer control capability 180 degree polarization rotation Continuous rotation of linearly polarized light Polarization purity is defined as the ratio of the rotated linear component to the orthogonal component. A selected rotation is very sensitive to applied voltage and operating temperature. On average, polarization purity (or contrast ratio) is better than 150:1. We provide test data including the required voltages corresponding to polarization orientations from approximately -40 to approximately 140 rotation in 10 increments. These measurements are taken at room temperature for your specified wavelength. Standard Polarization Rotators are supplied without an input polarizer. Input polarization direction must be precisely aligned for optimum performance. Please call if you require an input polarizer. Polarizers Retarders Mounting Hardware Devices Fig Operation of Polarization Rotator showing complete rotation of a linearly polarized input beam mlo@meadowlark.com (303)

54 Polarization Rotators Polarizers Retarders Mounting Hardware Specifications Retarder Material Nematic liquid crystal with Birefringent polymer Substrate Material Optical quality synthetic fused silica Wavelength nm (specify) Polarization Rotation Polarization Purity Transmittance Transmitted Wavefront Distortion (at nm) Surface Quality Beam Deviation Reflectance (per surface) Diameter Tolerance Temperature Range Recommended Safe Operating Limit 180 or more 150:1 average > 92% with polarized input λ/ scratch and dig 2 arc min 0.5% at normal incidence ±0.005 in. 0 C to 50 C 500 W/cm 2, CW 300 mj/cm 2, 10 ns, visible Ordering Information Diameter, D Clear Aperture, CA Thickness t Part Number LPR λ LPR λ LPR λ Please specify operating wavelength λ in nanometers when placing your order. Custom sizes are available. Please contact our Sales Department for a custom quote. Devices 54 (303) mlo@meadowlark.com

55 NEW High Contrast Optical Shutter Specifications Liquid crystal configuration Twisted nematic Substrate Material Optical quality synthetic fused silica Polarizer Material Dichroic Polymer Wavelength Range nm Contrast Ratio (average) 1,000:1 Angular Field of View 25 incidence angle with some reduction above 10 Switching Time (10% to 90%) at room temperature Closed to open: Open to closed Transmitted Wavefront Distortion (at nm) Surface Quality Reflectance (per surface) Beam Deviation Recommended Safe Operating Limit Glass Thickness Polarization Direction Storage temperature Operating temperature 5 milliseconds 0.4 milliseconds λ/ scratch and dig 0.5% at normal incidence 5 arc min 1 W/cm 2, CW inches Vertical on input face, horizontal on output face -20 C to +80 C 0 C to +50 C Key Benefits High Contrast No mechanical motion Computer control capability No vibration This liquid crystal shutter is a vibration-free alternative to mechanical shutter that is especially convenient for use in polarized light beams. The liquid crystal switches between a state that rotates the input polarization by 90 with no voltage applied and a state that makes no change in the input polarization with 8 to 10 volts applied. The applied voltage is 2 khz AC as supplied by our 4010, 3040 or 3050 liquid crystal drivers. The liquid crystal configuration is twisted nematic. The shutter is supplied with integral dichroic visible polarizers that function over the wavelength range of 450 nm to 700 to provide an average contrast ratio of better than 1,000:1 over this wavelength range. Shutters with larger aperture sizes and with wavelength coverage to 2.1 microns are available on a custom basis. Please call with your special requirements. Polarized Transmission (%) Polarized Transmission(%) Wavelength Fig Transmission for Polarized Light Ordering Information Diameter, D Clear Aperture,CA Thickness t Part Number LCS LCS LCS Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

56 Swift Principles Polarizers Retarders Mounting Hardware Devices Meadowlark Optics next generation liquid crystal variable devices utilizes a new bulk stabilized polymer liquid crystal formulation. With switching speeds of less than a 150 microseconds in both directions our new Swift devices are perfect for applications where response time is critical. Swift Technology Liquid crystal polymer composite materials have been studied extensively is the past decades because of their intriguing physics and their potential application in robust, fast-switching liquid crystal devices. Meadowlark Optics has developed a novel fabrication process in which a polymer network is utilized to enhance the electro-optical performance of our liquid crystal devices. (a) (b) (c) Typical bulk liquid crystal devices, such as Meadowlarks LCVR, have response times that are governed by the bulk of the liquid crystal and are a function of cell gap. As cell gap increases, switching times increase as the square of the thickness. This effect is due to molecular properties of the bulk liquid crystal material and the alignment layer of the cell (See Figure 4-6). The actual temporal electro-optical response of the cell has two components, (1) a very fast surface layer effect that occurs very close to the alignment layer and is on the order of microseconds and (2) a relatively slow response that occurs in the bulk of the material on the order of milliseconds. This second response dominates in a typical bulk liquid crystal device. Figure 4-17 (a) defines these two regions for a standard liquid crystal variable retarder cell. To overcome this effect the introduction of small amounts of polymer material into the bulk allow for a multitude of alignment surfaces for the liquid crystal material. This allows for alignment surface effects throughout the bulk of the cell (Figure 4-17 (b)). The addition of a polymer stabilizing material in the bulk essentially decouples the cell gap from the switching speed. The challenge to this type of device is now there are no means for uniform liquid crystal alignment in the bulk, such that after infiltration of polymer material; the liquid crystal is aligned in random fashion with no particular fast-axis for functional retarder devices. For liquid crystal alignment to occur Meadowlark Optics performs a mechanical shearing process on the devices that aligns the bulk liquid crystal material (Figure 4-17 (c)). Once this step is performed the cell is locked into place and sealed. This assembly process ensures excellent uniformity in alignment of the liquid crystal molecules and gives a retardance uniformity across the clear aperture of less than 20nm. Meadowlark Optics Swift liquid crystal technologies can be used throughout the visible and near infrared region. While these devices, like all liquid crystal devices, are affected by temperature and wavelength changes, they can be calibrated to accommodate those differences. Each Swift liquid crystal variable retarder is supplied with retardance versus voltage performance data for your specified wavelength, while our shutter devices are provided with temporal performance data. A coaxial cable with mating connector is provided for easy attachment to one of our new high voltage power supply sources. Fig (a) Typical bulk liquid crystal device showing both regions of fast and slow electro-optical response. (b) A polymer stabilized liquid crystal device showing random alignment in the bulk of the material. (c) A Swift device after alignment process (303) mlo@meadowlark.com

57 NEW Swift Variable Retarders Normalized Response Time (μs) Time (ms) Fig Swift Response Time Plot Key Benefits Sub-millisecond response times Computer control capability Temperature control options Performance from 450 to 1800 nm The next generation of liquid crystal variable retarders utilizes a new bulk stabilized polymer liquid crystal formulation. With switching speeds of less than a 150 microseconds in both directions the Swift Variable Retarder (SLCVR) is perfect for applications where response time is critical. The SLCVRs require a high voltage (< 100 Vrms) 13 khz square wave of adjustable amplitude that is provided by our D3060HV High Voltage Interface (see page 62). A temperature sensing and control option can be added to our SLCVRs for accurate controlling of the operating temperature. The thermal sensor is attached directly to the SLCVR substrate, outside the clear aperture. Custom SLCVRs are available for a variety of applications. Specifications Retarder Material Substrate Material Response Time (10-90%) Contrast Ratio Retardance Range Without compensator With compensator Transmitted Wavefront Distortion (at nm) Surface Quality Beam Deviation: Reflectance (per surface): Diameter Tolerance Polymer stabilized nematic liquid crystals Optical quality synthetic fused silica 175 ms (zero to half-wave) 175 ms (half-wave to zero) 150:1, minimum ~50 nm to λ/2 0 to λ/2 custom ranges are available λ/ scratch and dig 2 arc min 0.5% at normal incidence ± in. Polarizers Retarders Mounting Hardware Devices Retardance (nm) Voltage (V) Fig Swift Retardance vs Voltage Storage Temperature Operating Temperature Wavelength Range Ordering Information Diameter, D Clear Aperture,CA -20 C to 80 C 0 C to 55 C VIS: nm IR 1: nm IR 2: nm IR 3: nm Thickness t Without Attached Compensator (50 nm to λ/2) Part Number SVR With Attached Compensator (0 nm to λ/2) SRC Please specify spectral region when placing your order. mlo@meadowlark.com (303)

58 Polarizers Retarders Mounting Hardware Devices NEW Swift Optical Shutters Polarized Transmission (%) Polarized Transmission(%) Fig Polarized transmission of the Swift Optical Shutter in the open state Normalized Response Normalized Response Wavelength [nm] [nm] Time (μs) Time (ms) Fig Swift LC Response Time Plot Ordering Information Diameter, D Clear Aperture,CA Thickness t Part Number SCS Key Benefits No mechanical motion Computer control capability Noiseless High speed This liquid crystal shutter is a vibration-free alternative to mechanical shutters for use in high- speed shutter applications. It uses a Swift LC cell between crossed polarizers to provide submillisecond switching for both opening and closing. Switching time is 125 microseconds to open and 125 microseconds to close. The switching times are less than 50 microseconds if the shutter is heated to 40 C. The D3060HV controller provides this temperature control capability. These shutters show some haziness in the liquid crystal layer in the blue and green wavelengths. The light loss from this haze is about 1% at 700 nm but increases monotonically to about 10% loss at 450 nm. Scatter at wavelengths above 700 nm is negligible. The shutter is supplied with integral dichroic visible polarizers that function over the wavelength range of 450 nm to 700 nm to provide an average contrast ratio of better than 200:1. Shutters with larger aperture sizes and with wavelength coverage to 2.1 microns are available on a custom basis. Please call with your special requirements. Specifications Retarder Material Substrate Material Polarizer Material Wavelength Range Contrast Ratio (average) 200:1 Polymer stabilized nematic liquid crystals Optical quality synthetic fused silica Dichroic Polymer nm Angular Field of View ± 5 incidence angle Switching Time (10% to 90%) at room temperature Closed to open: Open to closed Switching Time (10% to 90%) at 40 C Transmitted Wavefront Distortion (at nm) Surface Quality Reflectance (per surface): Beam Deviation Recommended Safe Operating Limit Glass Thickness Polarization Direction Storage temperature Operating temperature 150 ms 150 ms 50 ms λ/ scratch and dig 0.5% at normal incidence 5 arc min 1 W/cm 2, CW 300 mj/cm 2, 10 ns, visible inches Vertical on input face, horizontal on output face -20 C to +70 C -10 C to +60 C 58 (303) mlo@meadowlark.com

59 Basic Controller Fig. 5-1 Internal Frequency Internal External Frequency/Voltage 1 Output Pulse Voltage Voltage 1 Voltage 2 Basic Controller Model D4010 Voltage 1 Voltage 2 Error Model D4010 Basic Liquid Controller front panel layout Meadowlark Optics is excited to announce the release of the Model D4010, our new Basic Controller. This liquid crystal (LC) driver is designed to integrate with any single (standard) Meadowlark Optics LC device currently offered as well as any nematic device compatible with the specifications listed. Digital LED voltage and frequency readouts provide added convenience. Now, frequency and voltage settings can be easily stored by simply pressing the adjustment knob. Also, system memory retains voltage and frequency settings at power down. With a Variable Retarder, manual adjustment of the voltage amplitude controls the device retardance. Figure 4-8 on page 49 illustrates the relationship between voltage and retardance. Independent voltage settings allow easy and repeatable selection of two retardance values. Often, it is desirable to modulate between the two states. For example, switching between quarterwave and half-wave retardance changes linearly polarized light to either left or right circular. A manual toggle allows easy switching between two states. Key Benefits: Convenient, stand-alone bench top operation Versatile - compatible with all standard Meadowlark Optics LC devices and other nematic liquid crystal devices with compatible listed specifications System memory retains voltage and frequency settings at power down Bright green, digital LED voltage and frequency readouts SMA and BNC outputs, with no adapters required Voltage and frequency save and restore function Out-of-the-box functionality. Sets up in minutes. Safe, low voltage operation. Fuse protected. Intuitive operation. Compact. Easy to use. ROHS and CE compliant Low DC bias protects liquid crystal Model D4010 comes equipped with its own internal modulation control. The Internal Frequency knob adjusts periodic switching between the two voltage settings. An external input allows modulation to run synchronously with other equipment. Each Meadowlark Optics Variable Retarder is supplied with a plot of its actual retardance versus voltage. Using your Model D4010 Controller and this retardance plot ensures accurate retardance to voltage correlation. Specifications Output Voltage Voltage Resolution Fundamental Drive Waveform External Modulation (input) Output Bias Power Requirements Internal Frequency (modulation) External Frequency (modulation) External Dimensions (W x D x H) CE Compliance Ordering Information Basic LC Controller 0 to 20 V rms, maximum ± 1 mv for < 10 V output ± 10 mv for 10 V output 2 khz ac square wave TTL compatible 5 V maximum ± 5 mv dc, maximum V ac Hz 500 ma Hz 50% duty cycle DC 500 Hz, variable duty cycle allowable 7.0 x 5.0 x 3.0 in. Compliant D4010 Two year and three year extended warranty options available, please contact your Meadowlark Optics sales engineer Polarizers Retarders Mounting Hardware Devices mlo@meadowlark.com (303)

60 Polarizers Retarders Four Channel Digital Interface Key Benefits: USB or RS232 interface C++ code examples including.dll libraries Compact and simple to use Microsoft HyperTerminal configuration file included Independent control of voltage levels on four channels to 1 mv resolution Includes National Instruments LabVIEW Virtual Instrument drivers to interface with custom software Mounting Hardware Devices The Four Channel Digital Interface is designed for high precision computer control of up to four Meadowlark Optics nematic liquid crystal devices at one time and is available in either Basic or Advanced Package options. The D3040 Basic comes with CellDRIVE 3000 Basic software to allow independent control of the amplitude of the 2 khz square wave drive for four separate nematic liquid crystal cells. The D3050 Advanced Package includes all the functionality of the Basic Package plus the added features of the CellDRIVE 3100 Advanced software and capability for temperature monitoring and control on one channel. The Advanced Package allows the amplitude of the 2 khz square wave output to be driven either by an external DC analog signal supplied to a front panel connector or specific CellDRIVE generated waveforms including sinusoidal, square, triangle, sawtooth and transient nematic effect waveforms. Additional functions include the capability to output a sync pulse on a front panel connector at desired points in the CellDRIVE generated waveforms and the ability to save/restore all CellDRIVE settings to/from a file. Fig. 5-2 Basic D3040 operation enables computer control for up to four Variable Retarders Fig. 5-3 Advanced D3050 operation can accommodate an external modulation signal via a convenient front panel connection 60 (303) mlo@meadowlark.com

61 Four Channel Digital Interface Specifications Fundamental Drive Waveform Modulation Amplitude Modulation Resolution DC Offset Communications Interface: LC Cell to Controller Connections Power Requirements CE Compliance Dimensions (L x W x H) Weight ADVANCED PACKAGE ONLY Modulation Waveforms Temperature Control (one channel only) Sync Output 2 khz ac square wave 0-10 V rms 1 mv (0.155 mv using LabVIEW subroutines) < 5 mv USB or RS232 SMA-SMB, 2 m cable length V ac Hz 500 ma compliant 9.50 x 6.25 x 1.50 in. 2 lbs. Minimum System Requirements PC with Pentium II class processor 32 MB RAM CD ROM drive 20 MB hard drive space USB or RS232 COM Port Windows 98/ME/2000/XP/Vista Use of LabVIEW Instrument Library requires LabVIEW version 6.1 or higher Ordering Information Basic Advanced external modulation input (0-5 V) sinusoidal triangle square sawtooth transient nematic effect Active heating/passive cooling to within ± 1 C of nominal set point TTL, 1 ms pulse, user specified phase D3040 D3050 Basic package includes: D3040 Controller Unit User Manual USB and RS232 cables Power supply and power cable CellDRIVE 3000 Basic Software National Instruments LabVIEW virtual instruments driver Advanced package includes: D3050 Controller Unit with external input and sync output front panel connectors User Manual USB and RS232 cables Temperature control cable LC-Controller interface cable Power supply and power cable Temperature monitoring and control CellDRIVE 3100 Advanced Software National Instruments LabVIEW virtual instruments driver NOTES: 1. D3040 may be upgraded to D3050 specifications. This upgrade also includes CellDRIVE Please contact a Sales Engineer for more information. 2. Previous generations of Meadowlark LC devices with TSC option may not be compatible with the TSC option in the D Previous generations of Meadowlark LC used BNC to SMB cables. Adapters and replacement cables are available. Please contact a Sales Engineer for assistance. 4. Temperature monitoring and control is only available on the D3050 and requires a liquid crystal device with the temperature sensing and control (TSC) option. Polarizers Retarders Mounting Hardware Devices SMA to SMB Cables SMA-SMB Two year and three year extended warranty options available, please contact your Meadowlark Optics sales engineer mlo@meadowlark.com (303)

62 Polarizers Retarders Two Channel High Voltage Interface Key Benefits: USB or RS232 interface C++ code examples (all required libraries included) Compact and simple to use Microsoft HyperTerminal configuration file included Independent control of voltage levels on two channels to 10 mv resolution Includes National Instruments LabVIEW Virtual Instrument drivers to interface with custom software Specifications Fundamental Drive Waveform 13 khz ac square wave Mounting Hardware Devices The Two Channel High Voltage Digital Interface is designed for high precision computer control of up to two Meadowlark Optics Swift LC liquid crystal devices at one time. The D3060HV Package includes all the functionality of the D3050 plus the high voltage circuitry necessary for Swift LC devices. CellDRIVE 3100 HV software includes all the features of the CellDRIVE 3100 Advanced software, but is optimized for the high-speed Swift LC devices. Also included is capability for temperature monitoring and control on one channel. The Advanced Package allows the amplitude of the 13 khz square wave output to be driven either by an external signal supplied to a front panel connector or specific CellDRIVE generated waveforms including sinusoidal, square, triangle, sawtooth and transient nematic effect waveforms. Additional functions include the capability to output a sync pulse on a front panel connector at desired points in the CellDRIVE generated waveforms and the ability to save/restore all CellDRIVE settings to/from a file. Package includes: D3060HV Controller Unit with external input and sync output front panel connectors User Manual USB and RS232 cables Temperature control cable LC-Controller interface cable Power supply and power cable Temperature monitoring and control CellDRIVE 3100 HV Software National Instruments LabVIEW virtual instruments driver Ordering Information High Voltage Controller D3060HV Modulation Amplitude Modulation Resolution DC Offset Communications Interface LC cell to Controller Connections Power Requirements Safety Feature Dimensions (L x W x H) Weight Modulation Waveforms Temperature Control (one channel only) Sync Output V rms 10 mv (1.55 mv using LabVIEW subroutines) < 50 mv USB or RS232 LEMO RF cable, 2 m length Vac Hz 2.5 A Minimum System Requirements PC with Pentium II class processor 32 MB RAM CD ROM drive 20 MB hard drive space USB or RS232 COM Port Windows 98/ME/2000/XP/Vista Use of LabVIEW Instrument Library requires LabVIEW version 6.1 or higher Keyed Interlock Switch x 7.25 x 4.0 in. 6 lbs. external modulation input (0-5 V) Sinusoidal Triangle Square Sawtooth transient nematic effect Active heating/passive cooling to within ± 1 C of nominal set point TTL, 1 ms pulse, user specified phase High Voltage Cable Swift LC Cable 62 (303) mlo@meadowlark.com

63 Systems Liquid crystals provide the basis for our system level products, which are spatial light modulators, polarimeters and tunable filters. These materials enable nonmechanical control of light through electrical manipulation of the polarization. More specifically nematic liquid crystal variable retarders provide electrical control of retardation and thus electrical control of: 1. Spatial distribution of phase or intensity in our spatial light modulators, 2. Polarization dependent time modulation of intensity in our polarimeters 3. Wavelength dependent transmission in our tunable filters. These systems are a natural extension of our expertise in polarization control to fulfill your needs for higher level functions in your laboratory or your systems. As with almost all our products these systems can be customized to meet your special requirements. Please call us if your requirements differ from our published specifications. mlo@meadowlark.com (303)

64 Spatial Light Modulator Principles Spatial Light Modulators Tunable Optical Filters Polarimeters Meadowlark Optics award-winning Spatial Light Modulators (SLMs) provide precision retardance control for spatially varying phase or amplitude requirements. Our SLMs consist of liquid crystal (LC) pixels, each independently addressed, acting as separate variable retarders. These SLMs are easily incorporated into optical systems requiring programmable masks and variable input/output devices. Applications include correlation, spectroscopy, data storage, ultrafast pulse shaping, optical computing, beam steering and wavefront correction for active and adaptive optics. Basic construction and operation of an SLM is similar to our standard LC Variable Retarder described on pages The ITO transparent conductor is photolithographically patterned into individual electrodes, creating independently controllable pixels. Standard SLM geometries are shown on page 65. Minimizing pixel spacing is critical to optimize performance and resolution. Proprietary designs and techniques enable Meadowlark Optics to offer tight interpixel spacing. Custom pixel configurations are possible. Phase Control Spatial phase control or modulation is accomplished without altering the intensity profile of an incident beam. Light linearly polarized parallel to the extraordinary axis of the LC material is phase modulated by the voltage applied across individual pixels. An optical path difference between adjacent pixels, tunable to one full-wave, is easily accomplished, as shown in figure 6-1. Spatial Light Modulator Applications Spatial Light Modulators are being used in a diverse range of new applications including: Microscopy Imaging polarimetry Optical data storage WDM gain flattening Wavefront correction Arbitrary pulse shaping Optical transform masks WDM add/drop modulators Multi-channel PMD correction Beam steering for live cell manipulation Holographic Displays Cinematography Optical Tweezers Astronomical Observation Fluorescence Photomasking Amplitude Control Spatial Light Modulators are also used for amplitude control or modulation. Here, the SLM modifies the beam intensity, but also spatially alters the phase profile, which may be undesirable. Correction is accomplished by using two spatial light modulators in series. The first performs the necessary amplitude modulation, also introducing a phase change. The second SLM restores the original, or desired phase relationship between pixels. Polarizers are optional with an amplitude SLM. These polarizers are both rotatable and removable from the SLM housing. The compact optical head is designed so that two units can be placed back-to-back, minimizing the path distance between modulators. Electrical connections exit one side of the optical head for convenience in handling and mounting. All Meadowlark Optics SLMs conveniently interface with Model D3128 Controller described on page 67. Fig. 6-1 With phase modulation, an optical path difference of up to one full-wave is produced between adjacent pixels of the Spatial Light Modulators. The output intensity remains uniform (303) mlo@meadowlark.com

65 Spatial Light Modulators Key Benefits High transmission Compact optical housing design Computer controlled Phase or amplitude modulation Uses model D3128 SLM Controller Meadowlark Optics Spatial Light Modulators (SLMs) consist of patterned arrays of independently controlled liquid crystal (LC) variable retarders. Our high-resolution SLMs are electronically programmable and interface to our Model D3128 SLM Controller. Meadowlark Optics offers both linear and hexagonal pixel geometries. Spatial Light Modulators Hex Spatial Light Modulator Our two dimensional SLMs are designed for adaptive optics applications. A two dimensional array of Variable Retarders acts as a real time programmable phase mask for wavefront correction of a linear polarized source. Unwanted aberration effects are removed by introducing the opposite phase shift through the Hex SLM. The most common applications involve high-resolution imaging where viewing through an aberrant medium is unavoidable. Examples include astronomical imaging with ground-based telescopes and medical imaging through body fluids. High-energy laser users also benefit from active phase compensation for beam profile correction. Linear Array Spatial Light Modulator The Linear SLM has a linear pixel array geometry. This system can be used to alter the temporal profile of femtosecond light pulses via computer control. Applications requiring these short pulses include analysis and quantum control of chemical events, optical communication and biomedical imaging. These SLMs find use in other applications including Hadamard spectroscopy, optical data storage and wavefront compensation. Fig. 6-2 Hexagonal SLM pixel geometry Tunable Optical Filters Polarimeters Fig. 6-3 Linear SLM pixel geometry w = 98 um and d = 4 um Custom Spatial Light Modulators are available. mlo@meadowlark.com (303)

66 Spatial Light Modulators Top View 7.00 End View Mounting Holes 8-32 Mounting Holes /4"-20 Mounting Hole /4"-20 Mounting Hole Mounting Holes 8-32 Mounting Holes Spatial Light Modulators Cable Slot 8-32 Mounting Holes on 4 inch centers Side View Tunable Optical Filters Polarimeters Fig. 6-4 Spatial Light Modulator Mechanical Drawing Specifications Retarder Material Nematic liquid crystal Substrate Material Optical quality synthetic fused silica Center Wavelength nm (specify) Modulation Range Phase (minimum) Amplitude Retardance Uniformity Transmitted Wavefront Distortion (at nm) Surface Quality Beam Deviation 1λ optical path difference 0-100% 2% rms variation over clear aperture λ/ scratch and dig 2 arc min Ordering Information Name Pixel Width (µm) 1 x 128 Hexagonal 127 Pixel Geometry 98mm x 4mm linear 1mm across Version Phase Amplitude Phase Amplitude Part Number SSP - 128P - λ SSP - 128A - λ Hex - 127P - λ Hex - 127A - λ Please specify your operating wavelength λ in nanometers when ordering. Two year and three year extended warranty options available, please contact your Meadowlark Optics sales engineer Transmittance Reflectance (per surface) Dimensions (L x W x H) Recommended Safe Operating Limit Temperature Range > 90% (without polarizers) 0.5% at normal incidence 7.00 x 2.96 x 0.74 in. 500 W/cm 2, CW 300 mj/cm 2, 10 ns, 532 nm 10 C to 45 C Note that the D3128 is included with purchase of the SLM system, see page 67 for specifications OPTIONAL POLARIZERS Type Wavelength Range (nm) Part Number Visible SDP - VIS Near Infrared SDP - IR1 Near Infrared SDP - IR (303) mlo@meadowlark.com

67 Spatial Light Modulator Controller Meadowlark Optics Spatial Light Modulator Controller allows for independent voltage control of up to 128 liquid crystal cells or pixels. The SLM Controller connects via USB cable to a Windows based computer. Supplied software allows for convenient setting of individual pixel retardance and for the programming of retardance profiles across a pixelated device. Custom software can be written using the included LabVIEW Virtual Instrument Library to allow for integration into custom applications. Spatial Light Modulators ORDERING INFORMATION Item Output Channels Part Number SLM Controller 128 D3128 Specifications Output Voltage Voltage Resolution Computer Interface 2 khz ac square wave digitally adjustable 0-10 V rms 2.44 mv (12 bit) USB Power Requirements V ac Hz 1 A Dimensions (L x W x H) 9.50 x 6.25 x 1.50 in. Weight 2 lbs. Minimum System Requirements PC with Pentium III class processor 64 MB RAM CD ROM drive 40 MB hard drive space USB Port Windows 98/ME/2000/XP/Vista Use of LabVIEW Instrument Library requires LabVIEW version 6.1 or higher Please note that the D3128 is included with purchase of the SLM system, see page 66 for specifications Tunable Optical Filters Polarimeters mlo@meadowlark.com (303)

68 Tunable Optical Filter Principles retarder as the waveplate enables the birefringence to be a function of the applied voltage. Thus by applying a different voltage, the location of the peaks can be moved and a filter can be tuned. Spatial Light Modulators A single Lyot Stage is generally not particularly useful, but if several of them are stacked together, the free spectral range can be increased, while the pass band remains about the same. The following figure shows how many Lyot Stages can work in concert to diminish every peak except for the one of interest (top line). Tunable Optical Filters Polarimeters Meadowlark Optics Tunable Optical Filters facilitate spectral analysis of not only a collimated beam, but also more importantly an entire object. The Tunable Filter passes only a narrow bandwidth of light while blocking all others within the designated spectral range. The pass band can be shifted to a new color in the blink of an eye. This combination of pass band and speed is equivalent to thousands of dichroic or interference filters on hundreds of filter wheels. This enables the user to acquire images at thousands of different wavelengths in a short amount of time. Applications of Tunable Optical Filters include fluorescence microscopy, absorption microscopy, Raman microscopy and solar astronomy. Tunable Optical Filter Basics A Tunable Optical Filter works on the principle of polarization dispersion. Simply stated, when light passes through a waveplate (e.g. a liquid crystal variable retarder), it will be retarded by a certain number of waves. When light of a different wavelength passes through the same waveplate, it will be retarded by a different number of waves. To illustrate this effect, consider a Lyot Stage. This Lyot Stage consists of two parallel (or crossed) polarizers placed around a waveplate, which is oriented at 45 degrees to the polarizers as shown. Transmission through the Lyot Stage obeys the following equation, T(λ) = T 0 cos 2 (bt/λ) where T(λ) is the transmission at wavelength λ, T 0 is the maximum peak transmittance, b is the waveplate birefringence and t is its thickness. The spectral response is shown in Fig 7-1 for a 1300 nm retarder as stage one. Using a liquid crystal variable Fig. 7-1 Example of multi-stage transmission behavior Solc Stages, like Lyot Stages, are also useful in building Tunable Filters. A Solc Stage consists of multiple waveplates at prescribed angles between parallel (or crossed) polarizers. One advantage of using a Solc Stage over a Lyot Stage is that Solcs have a wider null and a narrower peak than a comparable Lyot. Therefore, when using stacks of Solc Stages to build a Tunable Filter, it is possible to reduce the total number of stages needed. Meadowlark Optics uses Lyot Stages, Solc Stages and other proprietary types of stages to make Tunable Filters. This permits a Tunable Filter to have optimum peak transmission with a minimum of leakage (303) mlo@meadowlark.com

69 Tunable Optical Filters Standard Tunable Optical Filters A Tunable Optical Filter consists of multiple liquid crystal variable retarders and polarizers protected in a temperature-controlled housing. Temperature control is important since the birefringence of the liquid crystal variable retarders is a function of temperature as well as voltage. Each liquid crystal cell that goes into the Tunable Filter is made to be highly uniform in retardance using our propriety manufacturing processes. This produces the best uniformity of transmission wavelength across the clear aperture. VersaLight polarizers are generally used with remarkably low losses, producing a final filter with very high transmission. Additionally, the polarizers have very wide fields of view and can accommodate much higher flux than standard dichroic polarizers. The electronics controller supplies the appropriate voltages to each of the liquid crystal variable retarders and maintains the temperature of the housing. All of the calibration data for each variable retarder is stored into memory on the electronics controller. When commands are issued to the controller via USB and serial port; the calibration data are accessed and new voltages to each of the variable retarders are initiated simultaneously. To issue commands via USB or serial port from a computer, Polarized Transmission (%) Polarized Transmission (%) Transmission Peaks for TOF-VIS for TOF-VIS Wavelength (nm) Key Benefits Broad tuning range Uniform clear aperture High peak transmission Multiple control interface options Replace thousands of interference filters Stable performance over wide ambient temperature range FilterDRIVE software is provided. This software allows a user to input a desired wavelength value using a keyboard or mouse. Firmware serial commands are provided in the user s manual for those wishing to control tunable filters using their own custom software. Our filter housings are designed to be easy to integrate into existing optical systems. Mounting points are standard 8/32 threaded; and both apertures come with c-mount threaded aluminum mounts for easy attachment of optical components. Below are sample transmission curves for our standard products, specifications for our standard tunable filters are shown at the end of this section; we also build custom filters. Polarized Transmission (%) Polarized Transmission (%) Transmission Peaks for TOF-LNIR for TOF-LNIR Wavelength 1450 (nm) Spatial Light Modulators Tunable Optical Filters Polarimeters Fig. 7-2 Typical Filter curves for the TOF-VIS Fig. 7-3 Typical Filter curves for the TOF-LNIR mlo@meadowlark.com (303)

70 Tunable Optical Filters A. B. Spatial Light Modulators Document Verification: A. Ordinary Illumination B. Through Filter Tunable Optical Filters Solar Astronomy Fluorescence Microscopy Polarimeters Custom Tunable Optical Filters Meadowlark Optics excels at providing customized Tunable Filters for all kinds of applications. Whether you are doing astronomical imaging, microscopy, or remote imaging, we can find a solution that meets your needs. Since all components are made in-house, a wide range of customization is possible. Whether you would like a larger clear aperture, a narrower pass band, a wider field of view, a variable pass band, or more, we can do it. When deciding on specifications for a custom filter, it is important to remember that not all specs can be chosen completely independently. The most important spec to consider is the finesse, f, which is defined as is the ratio between the free spectral range (FSR) of the filter and the full width at half maximum (FWHM) of the pass band. Higher finesses are achieved by adding more stages and thus more optics, which leads to a more expensive filter and also to lower peak transmission. Peak transmission is another important specification. This is defined as the maximum transmission of the pass band curve. Additionally peak transmission is generally reported for light that is polarized along the transmission axis of the first polarizer in the Tunable Filter. If unpolarized light is incident on the filter then the peak transmission will be half of the polarized peak transmission. The peak transmission is a function of the center wavelength of the pass band as well as the number of optics in the Tunable Filter. This means that the peak transmission is highly dependent on the optical finesse, since higher finesses have more optics and hence more absorptive elements. Other specifications include field of view, which defines the applicable half-cone angle from the optical axis for which the filter performance is guaranteed. Thus the rays entering the Tunable Filter should be kept less than this angle. If this is not possible, the main result will be a decrease in the out-of-band rejection. Out-of-band rejection is the measure of how much light, which is not within the pass band, gets through the filter; it is usually desirable to have the out-of-band rejection as high as possible. Other specifications including the tuning accuracy of the peak transmission can be optimized in Custom Filters. Meadowlark Optics has several proprietary and patent-pending designs for Tunable Filters. If you are interested in a Custom Tunable Filter with a very wide field-of-view, a variable FWHM (i.e. several different FWHMs possible at a particular wavelength) or any important specifications, please call us to discuss custom filter requirements. Applications: Remote Sensing Solar Astronomy Document Verification Hyperspectral Imaging Fluorescence Microscopy Biological/Chemical Imaging Pharmacological Development Chromographic Analysis Filter wheel replacement 70 (303) mlo@meadowlark.com

71 Tunable Optical Filters 2.25" 4.00" 0.72" DB-25 DB " 4.00" C-Mount Thread C-mount C-Mount Threads 0.24" 0.31" 0.31" 0.24" Top View 5.44" 0.75" Flattened chord 0.97" 1.40" Flattened Chord 0.97" Front View 1.40" Flattened Chord Front View Spatial Light Modulators 8-32 Thread Specifications AND ORDERING INFORMATION 0.413" 0.413" Bottom View Fig 7-4 Tunable Optical Filter Mechanical Drawing Bottom View Standard Filters Part Number TOF-VIS TOF-NIR Design Space (requires specification tradeoffs) Custom Filters TOF-1075 (custom example) Wavelength Range nm nm nm nm Clear Aperture Diameter 20 mm 20 mm mm 20 mm Full Width at Half Max (FWHM) (increases with λ) nm nm 0.1 to 100 nm nm Polarized Peak Transmission 5-60% 10-55% 80% max (based on design) 56% Tuning Resolution 0.1 nm 0.1 nm ~ 2% FWHM nm Tuning Accuracy FWHM/10 FWHM/10 Based on design FWHM/10 Field of View (Half Cone Angle) 6 3 Based on design 3 Switching Speed < 100 ms < 100 ms 10 to 500 ms < 100 ms Temperature Range 10 C - 35 C 10 C - 35 C 10 C - 35 C 0 C - 35 C Out-of-Band Blocking > OD2 Power Requirements V ac Hz 2A Controller Dimensions (L x W x H) 9.50 x 6.25 x 1.50 inches Controller Weight 2 lbs. Minimum Systems Requirements 0.413" 0.413" 0.75" Flattened chord 8-32 Thread PC with Pentium II class processor 32 MB RAM CD ROM drive 20 MB hard drive space USB or RS232 COM Port Windows 98/ME/2000/XP/Vista Use of LabVIEW Instrument Library requires LabVIEW version 6.1 or higher Tunable Optical Filters Polarimeters mlo@meadowlark.com (303)

72 Polarimeters Applications: Ellipsometry Test and Measurement Materials Characterization Spectroscopic Applications Telecom Device Manufacturing Pharmaceutical Development and QC Stokes Vector Analysis Spatial Light Modulators Tunable Optical Filters Polarimeters Meadowlark Optics has a longstanding reputation for precision polarization control and metrology. Our line of user-friendly Polarimeters provides this same high accuracy and reliability in an easy to use instrument, suitable for manufacturing and laboratory applications. These Polarimeters are compact, state-of-the-art systems with convenient computer control that accurately measures Stokes Parameters 10 times per second that quantify the State of Polarization (SOP) and then graphically displays this state on the Poincaré Sphere, Polarization Ellipse, or running chart. It contains no spinning waveplates, motors, or other moving parts to wear or cause vibrations. Patented, proprietary algorithms provide high accuracy and calibration versatility. Two models offer calibrated polarization measurement over the wavelength ranges 450 nm to 1100 nm and 900 nm to 1700 nm. Meadowlark Optics Polarimeters are computer-controlled with USB interface for increased measurement rate and convenience. PolarView 3000 User Interface Software Features: Data Averaging Stokes Parameters Polarization Ellipse Degree of Polarization Continuous Save To File Continuous Chart display Option Poincaré Sphere with 2D Projections Continuous Tracking On Poincaré Sphere Polarimeter Package includes: Temperature Controlled LC Polarimeter Optical Head D3000 Digital Electronic Controller PolarView 3000 software installation CD User Manual USB and optics head cables Power supply and Power cable Calibration at up to three wavelengths included (Storage in memory of up to 12 wavelengths possible) LabView Virtual Instrument Library for Polarimeter One year of software support and upgrades One year warranty for defects in materials and workmanship 72 (303) mlo@meadowlark.com

73 Polarimeters Key Benefits Compact No moving parts Stokes Vector Accuracy better than 1% Polarization state tracking Software Instrument Library Fiber and free space versions User-friendly graphical interface Visible and near infrared versions Ordering Information Wavelength Range (nm) Version Part Number Visible PMI - VIS Near Infrared PMI - NIR Optional Accessories: Eigenstate Generator Set* Fiber optic cable adapter - Visible - Near Infrared Angle-polished fiber collimator adapter Calibration at additional wavelengths * The Eigenstate Generator Set enables precise recalibration of your Polarimeter. See page 74 for additional information. Specifications Wavelength Ranges (nm) Visible Near Infrared Max Absolute Degree of Polarization Error Wavelength Range for Calibration Accuracy Measurement Frequency Resolution Maximum Operating Temperature Optical Head Dimensions Minimum Optical Power to maintain accuracy Power Requirements Input Aperture % ± 3 nm 10 Hz of a Stokes Parameter 40 C 2.83 x 1.75 x 1.75 in. 10 mw sensitivity can be increased to 1 mw by special request V ac Hz 500 ma 2 mm These specifications describe performance at 23 ± 3 C ambient temperature. Minimum System Requirements: PC with Pentium II class processor Windows 98/ME/2000/XP/Vista CD ROM drive 20 MB hard drive space 32 MB RAM USB Port Use of LabView Instrument Library requires LabView version 6.1 or newer full development system. system. Custom versions are available. Two and three year extended warranty options are available, please contact your Meadowlark Optics Sales Engineer. Spatial Light Modulators Tunable Optical Filters Polarimeters mm Mounting Holes on Centerline of Head Tapped 8-32 Mounting Hole Locations Front Fig. 8-1 Polarimeter Mechanical Dimensions mlo@meadowlark.com (303)

74 Eigenstate Generator Set Calibration Stokes SOP Polarizer Waveplate Sequence Vector Description Orientation Orientation Step 1 (1,1,0,0) Horizontal Removed Step 2 (1,-1,0,0) Vertical Removed Step 3 (1,0,1,0) +45 Removed Spatial Light Modulators Tunable Optical Filters Polarimeters Applications: Ellipsometry Polarization Control Polarization Analysis Calibration Accessory for PMI Series Polarimeters Meadowlark Optics Eigenstate Generator Set is a tool which produces six polarization eigenstates: linear polarized light at angles of 0, 90, +45, -45 degrees as well as circular right handed and circular left-handed polarized light. These states are created by using a precision dichroic linear polarizer in a black housing and a precision quarter waveplate in a blue housing. The housings are CNC machined so that the accuracy of the angles is better than 1 arc minute. Pins on the housings mate to a v-groove and a flat groove in a quasi-kinematic fashion, while magnets provide holding force. This scheme facilitates precise, simple and fast indexing of the polarization eigenstates. Large arrows on the housing indicate the transmission axis of the polarizer and the fast axis of the waveplates for ease of use. Available for wavelength ranges from nm. Eigenstate Retarders are additional retarders that can be purchased at the same time as your Eigenstate Generator set and polarimeter. Wavelengths available from nm. Step 4 (1,0,-1,0) -45 Removed Step 5 Step 6 Fig.8-2 (1,0,0,1) Right Circular (1,0,0,-1) Left Circular Polarimeter calibration is greatly simplified by the Eigenstate Generator Set sequence outlined above Fig. 8-3 Poincaré Sphere showing six polarization eigenstates Ordering Information Item Eigenstate Generator Set Eigenstate Retarders Part Number EGS-λ EGR-λ Please specify your operating wavelength λ in nm when ordering Diameter 0.4 Diameter Shoulder Screws 0.500" Head Diameter Top View ± Polarizer Front View Retarder Front View 3.00 End View Bottom View Bottom View Fig. 8-4 Polarizer, Retarder, Base 74 (303) mlo@meadowlark.com

75 Engineering Services Innovation doesn t just happen you need the right people in the right place Meadowlark Optics is that place and we have the right people. Whether your requirements are large or small, simple or complex, Meadowlark can design precision optics and mounting for your applications. Meadowlark s team of researchers and engineers can help you solve your polarization optics and instrumentation problems. We have developed custom polarizers, polymer retarders, achromatic retarders, liquid crystal optics and polarization analysis instrumentation. Our skilled production staff can turn your custom designs into consistently manufactured products. Meadowlark Optics has the expertise, facilities and instruments to ensure your parts are mounted and aligned exactly as required. Our group of Opto-Mechanical Engineers can build a mount to meet customer specifications using the latest CAD software and develop prototypes in our in-house machine shop. Plus, our collection of optical instruments, including proprietary devices, allows for mounting and verification of extremely tight optical and mechanical specifications. Working with Meadowlark Optics permits the entire process from design to volume manufacturing to be completed in the same building. This removes the hassle of transferring valuable information and losing time as different companies, development groups or manufacturing houses get up to speed on the changes. Here are a few of our custom polarization solutions... Capabilities Quality Ordering mlo@meadowlark.com (303)

76 Capabilities Small Precision Optics Custom Tunable Filters Capabilities Quality Ordering As optical components become integrated into OEM devices there is a need to restrict the dimensions of these components to ensure total package size requirements can be met. More importantly the parts must be manufactured without any loss in quality or optical characteristics. Meadowlark Optics has developed processes that allow us to efficiently build small polarizers and retarders, down to a few millimeters on a side for square parts or as tiny as 6 mm in diameter. Our unmounted PolyWave retarders can be built down to a millimeter per side with a usable clear aperture that extends to within 15 microns of the edge. Amazingly, these advancements are not only restricted to static components. Our active liquid crystal devices have gone even smaller than static parts, including some devices with a 1 mm circular clear aperture inside of a 3mm square device. Custom Mounts/Sub-Assembly Work When designing an optical instrument there are often difficult challenges that force optics to be installed in tight spaces to even tighter tolerances. Custom mounts are often required to hold components of varying sizes and shapes that cannot be supported by traditional mounting options. Sub-assemblies often require polarization components be mounted with sub degree accuracy, or be tilted to very specific angles away from normal incidence. Many applications require that researchers and scientists visualize minute concentrations of elements or compounds, or the changes in a continuous wavelength range. Meadowlark Optics line of Tunable Optical Filters allows the user to dissect an image into hundreds of individual wavelength images. Solar astronomers have used LC Tunable Filters for years (examples: imaging of solar flares and prominences or imaging the solar chromosphere) and now new applications in microscopy, spectroscopy, hyperspectral imaging and many other fields are being discovered and tested every day. Design and construction of Tunable Optical Filters combines multiple areas of Meadowlark Optics expertise, including our Variable Retarders, instrumentation, fabrication and of course polarization. Our knowledge has lead to designs that overcome many issues that have been overlooked in the past. For example, the retardance of a LC cell is sensitive to temperature and variations in the environment surrounding the device can lead to measurement errors. As a result we have mounted our Tunable Optical Filter inside a thermally controlled housing to preserve the tuning accuracy of the device. Meadowlark Optics offers a line of standard visible and near infrared Tunable Optical Filters that provide the insight and visualization you need. If the specifications of our standard devices are not ideal for your application we are very interested in designing a custom Tunable Filter to exactly meet your needs. Choose the wavelength range, full width at half maximum (FWHM) of the transmission peaks, tuning resolution, angular field-of-view and a number of other requirements and Meadowlark Optics will design the system needed to complete your experiments. We even have designs that allow for a variable FWHM at a single wavelength! Please refer to the Tunable Optical Filter section of the catalog (page 68) for more detail on these systems or call us to discuss your application requirements (303) mlo@meadowlark.com

77 Capabilities Custom Spatial Light Modulators The applications for Spatial Light Modulators (SLMs) are broad and far reaching. From ultrafast laser pulse shaping to wavefront correction many tasks can be completed with our standard Linear and twodimensional Hexagonal arrays. However, certain applications require larger active areas (clear apertures) in order to modulate the entire beam profile or maybe the pixels need to be arranged in a custom layout, like a series of concentric circles, for the experiment to be completed properly. Meadowlark Optics would like to take on your need for a custom designed transmissive SLM. Modifications to the pixel size, dimensions and pattern can be completed by creating a new photo-mask and since the optical head, driver and software can be kept the same these changes can be completed without dramatic price increases or lead-times. VersaLight Beam Splitting Polarizer In an effort to offer more versatile products Meadowlark Optics has designed an extremely broadband (650 to 2000 nm) polarizing beamcube based around our line of VersaLight wire grid polarizers. Laminating a Versa- Light polarizer inside two right angle prisms allows the component to exhibit the benefits of both the polarizer and cube. This means that you have an extremely broadband cube with a large acceptance angle that is easy to mount. These cubes can be made to transmit any polarization direction while reflecting the orthogonal polarization. Most broadband polarizing beamcubes offer a useable wavelength range of nm. The VersaLight beamcube offers a useable range of 1350 nm and can be used from nm without much variation in transmission or loss of contrast ratio. In fact, this cube has a transmitted contrast ratio of 500:1 or better through most of the useable wavelength range. It also pushes the limits of the field of view for polarizing beamcubes. The angular acceptance of the VersaLight cube is greater than ± 20, compared to ± 3 for most thin film beamcubes, opening up many uses and applications that were not possible with thin film polarizer designs. This cube continues the Meadowlark Optics tradition of innovation and quality construction by providing better specs and more performance to our customers, allowing them do to and see things that were never possible before. Custom Retarders When completing an application where the wavelength of interest is different from a standard light source wavelength it can be difficult to find an accurate retardation plate. The cost of polishing an entire batch of crystal parts (quartz, magnesium fluoride, sapphire, etc.) will make the prices of low quantities of these retarders very expensive. Using our polymer processing facilities, Meadowlark Optics can create a custom retarder for your specific wavelength. Custom retardances, such as eighthwave or tenth-wave are also available. We also have the ability to create retarders with custom dimensions or large areas to fit perfectly within your unique optical design. Micro Retarders Other distinctive retarders that Meadowlark Optics can produce include a product we call Micro Retarders. These components were originally designed for use inside telecommunications systems and their primary characteristic is their thickness, or more appropriately their thinness. These retarders measure less than 20 microns thick, less than five millimeters per side and have almost perfect transmission characteristics. Like our standard polymer retarders these parts are available for any wavelength and any retardance. Capabilities Quality Ordering mlo@meadowlark.com (303)

78 Capabilities Capabilities Quality Ordering Pockels Cell Modulators Our longitudinal Pockels Cells are often used in polarimetry on imaging light beams and in the chopping of polarized beams. They consist of Z-cut KD*P crystals between protective windows that have transparent indium-tin oxide electrodes applied to their interior faces. The electrodes produce a uniform electric field normal to the optical faces and permit use of a thin (less than 3 mm) KD*P crystal. This makes these cells suitable for use in non-collimated imaging light beams slower than f/20. Meadowlark specializes in clear aperatures up to 40 mm. These devices are useful as variable retarders in applications requiring much faster switching Unique Custom Capabilities Over the years Meadowlark Optics has been asked to deliver some unique polarization components. Our reputation for quality and innovation has made us the company that many people turn to when they need a device that is not readily available. Examples of these devices include a segmented polarizer that contained four different quadrants, where each quadrant had its polarization transmission axis in a different orientation. Another is an assembly of polarizing beamcubes that can take an input beam and separate it into multiple output beams with varying linear polarization directions. We also have manufactured an optically addressed spatial light modulator. Our engineers have spent years designing these components for various applications and they have the imagination and knowledge to build a component that will perfectly fit your needs. So if you have an idea for a polarization component that you cannot find anywhere else talk to Meadowlark Optics. Engineering Services/Consulting When faced with a problem related to polarization it can be very difficult to come to a solution that takes into account all of the issues that need to be considered. Many times optimizing one parameter of a system leads to degradation somewhere else and these tradeoffs need to be characterized in order to create the best system possible. The engineers at Meadowlark Optics have the educational background, technical knowledge and most importantly years of experience to help you properly identify and solve the problems you face. Outside of their personal experiences our engineers have access to numerous polarization modeling and simulation programs that can compute the expected polarization output after an arbitrary polarization state is passed through any number of components. When modeling does not provide enough information we have a number of state of the art optical measurement systems and techniques that measure retardance down to of a wave or angular accuracies of less than half a degree. So when faced with a polarization problem that threatens to slow down your progress contact Meadowlark Optics and allow our group of engineers to provide you with the correct solution (303) mlo@meadowlark.com

79 Meadowlark Quality Standards At Meadowlark Optics, people are our strength and we believe in providing them with the best tools to do the job. The precision and quality our customers demand are part of everything we do. At the heart of our process is our precision metrology. This automated ellipsometer provides fast, accurate retardance measurements. Capabilities Quality Ordering Proprietary analytical tools, state-of-the-art system and component designs, as well as computer-controlled manufacturing equipment come together to ensure quality and consistency in all Meadowlark Optics products. All our optical components and instrumentation are assembled to some of the most exacting standards in the industry by our highly trained staff. We take precision seriously and we back it up with our warranty. (303)