:... resolution is about 1.4 μm, assumed an excitation wavelength of 633 nm and a numerical aperture of 0.65 at 633 nm.

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1 PAGE 30 & PRODUCT CATALOG Confocal Microscopy - CFM fundamentals :... Over the years, confocal microscopy has become the method of choice for obtaining clear, three-dimensional optical images of sample structures. It has been used for imaging almost everything - from studying biological samples such as cells, to fluorescence measurements, to examining physical structures like semiconductor quantum dots, NEMS/MEMS devices and for the emerging area of nano-optics. The confocal imaging system achieves out-of-focus rejection by two strategies (schematically illustrated in the figure to the right): 1. By illuminating a single point of the specimen with a focussed beam. Thus, the illumination intensity drops rapidly above and below the plane of focus. 2. By using of a blocking pinhole in the conjugate plane to the specimen that eliminates the degrading out-of-focus information. By scanning many thin sections through the sample, a very clean three-dimensional image can be obtained. Confocal imaging can offer another advantage in favourable situations (small pinhole size, bright specimen): the obtained resolution can be better than with any microscope operated conventionally. In practice, the best horizontal resolution of a confocal microscope is about 0.4 μm, and the best vertical resolution is about 1.4 μm, assumed an excitation wavelength of 633 nm and a numerical aperture of 0.65 at 633 nm. This resolution can be further improved by combining confocal microscopy with solid immersion lens microscopy, where light is focused inside a high refractive-index lens close to the sample. This offers a method for achieving resolution well below the diffraction limit in air. With an illumination wavelength of 633 nm, a lateral resolution of 160 nm could be achieved in the attocube systems application lab. Combining these techniques, major improvement of resolution and light throughput are achieved in addition to offering a very simple experimental setup compared to other high resolution optical techniques, e.g. Scanning Near-field Optical Microscopy (SNOM). Cryogenic Confocal Microscopy To improve the image quality in high resolution microscopy, confocal microscopy is often used at cryogenic temperatures. Thus, combination of high resolution power, clear optical spectrums and reduced thermal noise can be achieved. Spectral lines become sharper as thermal broadening is reduced due to lower thermal energy present in the system. Optical signals become stronger as quantum efficiency is improved due to less scattering and non-radiative recombinations. For many optical microscopy applications, cryogenic temperatures are therefore inevitably required. These advantages are profitable particularly for high resolution optical spectroscopy of semiconductor structures or single molecule detection. Thus, investigation of the emitted optical energy of the sample due to changes in the surrounding material, applied voltages, or the deposited optical energy becomes feasible. Additionally, high spatial resolution and sharp spectral lines are a prerequisite for investigating photon anti-bunching (single photon emitters). attocube systems explore your nanoworld

2 PAGE 31 & PRODUCT CATALOG overview and important facts... attocube systems CFMs Laser Excitation Light Rays Blocking Pinhole Light Source Detector Blocking Pinhole Detector Out-of-Focus Light Rays In-Focus Light Rays Semitransparent Mirror Objective A decade of experience in low temperature optics led to the development of three complementary confocal microscope systems optimized for different applications. All attocube microscope systems are compatible with vacuum environments as well as high magnetic fields. attocfm I: This system based on free beam optics has been developed to offer highest flexibility to the customer. The modular beam splitter head is mounted outside of the cryostat and, thus, the experiment can be adjusted to the customer s requirements. attocfm II: The key-feature of this system is its unreached stability allowing ultra stable long-term investigations. This is also the most compact system which is available for 2 inch and 1 inch (attocfm IIxs) bore size cryostats. Focal Plane attocfm III: This is the system of choice for customers interested in reflection as well as transmission microscopy. Similar to the attocfm II, it is also a fiber-based system. Sample nanoscopy Scanning Probe Microscopes for Extreme Environments

3 PAGE 32 & PRODUCT CATALOG Cutting Edge Developments :... Ultra low temperature confocal microscopy Spatial mapping of carbon nanotubes Intensity (counts / sec) steps in y-direction steps in x-direction G-band signal Raman shift (cm -1 ) excitation: 745 nm sample: CVD-grown nanotubes on Si/SiO2 substrate Currently under development is the implementation of a confocal microscope setup (attocfm II) into a dilution refrigerator for measurements at temperatures < 50 mk. This opens up new possibilities in the field of semiconductor research. Step scanning and mapping of a carbon nanotube using the integrated G-band signal; step size = ~ 700 nm (data recorded by Dr. A. Högele of the Quantum Photonics Group, ETH Zürich, Switzerland). attocube systems explore your nanoworld

4 PAGE 33 & PRODUCT CATALOG Closed loop positioners for easy-to-use CFMs Magnetic field dependence of quantum dots The closed-loop positioners ANP100/RES with resisitve position encoders allow for trouble-free orientation on the sample and refinding your spot of interest with an absolute reproducibility of ~ 1 mm over 6 mm coarse positioning range. Particularly for the attocfm III, alignment of excitation and collection fiber becomes now an easy task. Photoluminescence intensity of a triply charged InAs quantum dot vs. magnetic field (red corresponds to high intensity) recorded at cryogenic temperature using the attocfm II ( Hybridization of electronic states in quantum dots through photon emission by K. Karrai et. al., Nature (2004) 247, 8, 135). Confocal Microscopy nanoscopy Scanning Probe Microscopes for Extreme Environments

5 PAGE 34 & PRODUCT CATALOG attocfm I low temperature scanning confocal microscope, highly modular and flexible :... The attocfm I has been developed to offer highest flexibility in order to enable adaptation of the experimental setup according to the customer s needs. This flexibility is realized by the modular beam splitter head which is positioned outside of the cryostat. Furthermore, the free-beam optical design allows to adjust the excitation and the collection port completely independent. Thus, filtering of the excitation and collection signal enables also applications as e.g. Raman spectroscopy. The easy handling opens up new possibilities in quantitative surface characterization in the submicron range. Laser Collection Fiber Illumination Fiber Detector Lenses CCD Beam Splitter Vacuum Window Thin-Walled Stainless Steel Vacuum Tube COMPATIBLE COOLING SYSTEMS (see page 6) > LTSYS-He4 PRODUCT KEY FEATURES > modular beam splitter head outside of cryostat > highest flexibility > excitation and colletion ports fully adjustable > wavelength and polarization filtering of the excitation and collection signal possible Scanner EXAMPLE APPLICATIONS > solid state physics and quantum dot optics > high resolution defect analysis and topography profiles liquid He > raman spectroscopy > materials science research on ceramics, polymers, additives, alloys,.. Schematic drawing of the confocal setup attocfm I. x-axis y-axis z-axis Lenses Sample Superconducting Magnet (optional) Ultra Stable Titanium Housing attocube systems Positioning Stages Liquid He Dewar (optional) attocube systems explore your nanoworld

6 PAGE 35 & PRODUCT CATALOG... Principle - A schematic drawing of the confocal setup in attocfm I is shown to the left. A laser beam is coupled into a single mode optical illumination fiber. Part of this light is reflected on the beam splitter and focused on the sample (free-beam optics inside cryostat). The reflected light from the sample is captured by the collection fiber, which is also the blocking pinhole aperture when collecting the scattered light from the sample for the confocal setup. Objective Systems - attocube systems offers several objectives which can be adjusted depending on your experimental requirements, the wavelength range, working distance, and other parameters. For customized solutions, please contact our office. A color-scale plot of the photoluminescence (PL) versus gate voltage showing the discrete spectral lines of a quantum dot recorded with the attocfm I at a cryogenic temperature of 1.6 K. ( R. J. Warburton et. al., Optical emission from a charge-tunable quantum ring, Nature (2000) 405, 926). The attocfm I beam splitter and microscope module. Confocal image of a chess board grating (SiO 2 on Si) with a period of 2 μm, recorded in reflection mode. The sample has some defects on the surface structure which are clearly resolved. The image was recorded with the attocfm I in reflection mode. (attocube application labs, 2003). nanoscopy Scanning Probe Microscopes for Extreme Environments

7 PAGE 36 & PRODUCT CATALOG Specifications attocfm I Complete System Confiiguration For Low Temperature SPM NANOPOSITIONING Ultra-Compact Positioners for extreme Environments NANOSCOPY Scanning Probe Microscopes for extreme Environments attocontrol SPM-Controller Soft- and Hardware attooptions Options for Positioning and Microscopy Contact attocube s sales engineers for complete system configurations: attocube systems explore your nanoworld

8 PAGE 37 & PRODUCT CATALOG attocfm I Complete microscope stick attocfm I. nanoscopy Scanning Probe Microscopes for Extreme Environments

9 PAGE 38 & PRODUCT CATALOG attocfm II & attocfm IIxs low temperature scanning confocal microscopes, highly stable and compact :... The attocfm II is an ultra compact confocal microscope which is miniaturized for in-situ analysis. The microscope is highly stable at low temperature, high magnetic field, and high vacuum. Moreover, all mechanical parts are thermally compensated. The design is optimized to minimize the light losses and to capture the maximum amount of light scattered by the illuminated point of the sample. This one-of-a-kind combination of materials allows absolutely stable single dot measurements at low temperature over weeks, even when refilling a bath cryostat with liquid Helium. Furthermore, combination with cryogen-free cooling solutions is enabled. That opens up new possibilities in cryogenic long-term investigations. A new dimension of miniaturization has been realized by adapting the attocfm II for cryostat / dewar bore sizes down to 1 inch! The attocfm IIxs enables highest quality optical investigations with minimal spacial requirements. Laser L Detector 1 Detector 2 (optional) Coupler Illumination / Collection Fiber Vacuum Window Thin-Walled Stainless Steel Vacuum Tube COMPATIBLE COOLING SYSTEMS (see page 6) > LTSYS-He4 / LTSYS-He3 / LTSYS-HeDIL > LTSYS-Cc / LTSYS-CcADR / LTSYS-CcDIL PRODUCT KEY FEATURES > miniaturized for in-situ analysis > highest stability enables long term experiments > minimal light loss for highest sensitivity > optimized stability in high magnetic fields > ultra compact version for 1 inch (25.4 mm) setups available Scanner x-axis y-axis z-axis Low Temperature Compatible Objective Sample Superconducting Magnet (optional) Ultra Stable Titanium Housing attocube systems Positioning Stages EXAMPLE APPLICATIONS > solid state physics and quantum dot optics > fluorescence observation > highly stable long term experiments on single quantum dots > biological and medical research on tissue samples in cytological and neurological applications > fast 3D-imaging liquid He Schematic drawing of the confocal setup attocfm II. Liquid He Dewar (optional) attocube systems explore your nanoworld

10 PAGE 39 & PRODUCT CATALOG... Principle - A laser beam is coupled into one arm of a single mode optical fiber coupler. The fiber end of the second arm is placed in a ceramic ferrule to guarantee an accurate position of the fiber in the objective axis. This single mode fiber illuminates the sample and plays the role of the blocking pinhole aperture when collecting the scattered light from the sample. Objective Systems - Objectives with a large working distance of up to 7 mm or with a numerical aperture of up to 0.65 are available. An overview on the 4 different objectives available is listed in the table in the low temperature confocal objectives section. An increase of the numerical aperture by a half ball sapphire lens (solid immersion lens) is possible, thus leading to a resolution of nm (with red laser light illumination). Photoluminescence intensity of a triply charged InAs quantum dot vs. magnetic field (red corresponds to high intensity) recorded at cryogenic temperature using the attocfm II. (K. Karrai et. al., Hybridization of electronic states in quantum dots through photon emission, Nature (2004) 247, 8, 135). The ultra compact attocfm IIxs module. The attocfm II module. Confocal image of a tweezers structure; the tweezers are freely suspended. The size of the image is 30 x 30 μm recorded in reflection mode. The 200 nm wide structures are resolved with an excitation laser source of 630 nm. (C. Meyer et al., Slip-stick step-scanner for scanning probe microscopy, Rev. Sci. Instrum. (2005) 76, ). nanoscopy Scanning Probe Microscopes for Extreme Environments

11 PAGE 40 & PRODUCT CATALOG Specifications attocfm II Complete System Confiiguration For Low Temperature SPM NANOPOSITIONING Ultra-Compact Positioners for extreme Environments NANOSCOPY Scanning Probe Microscopes for extreme Environments attocontrol SPM-Controller Soft- and Hardware attooptions Options for Positioning and Microscopy Contact attocube s sales engineers for complete system configurations: attocube systems explore your nanoworld

12 PAGE 41 & PRODUCT CATALOG attocfm II Complete microscope stick attocfm II. nanoscopy Scanning Probe Microscopes for Extreme Environments

13 PAGE 42 & PRODUCT CATALOG Specifications attocfm IIxs Complete System Confiiguration For Low Temperature SPM NANOPOSITIONING Ultra-Compact Positioners for extreme Environments NANOSCOPY Scanning Probe Microscopes for extreme Environments attocontrol SPM-Controller Soft- and Hardware attooptions Options for Positioning and Microscopy Contact attocube s sales engineers for complete system configurations: attocube systems explore your nanoworld

14 PAGE 43 & PRODUCT CATALOG attocfm IIxs ULTRA COMPACT DESIGN FOR 1 -SETUPs The ultra-compact attocfm IIxs. nanoscopy Scanning Probe Microscopes for Extreme Environments

15 PAGE 44 & PRODUCT CATALOG attocfm III low temperature confocal microscope, optimized for transmission measurements :... The attocfm III is a highly stable, compact cryogenic microscope optimized for reflection and transmission experiments. The attocfm III confocal microscope is thermally compensated and guarantees stability for spectroscopy over months. It opens up new possibilities in quantitative sub-micron range investigations and routine inspection in extreme environments: temperatures down to 0.3 K, magnetic fields up to 15 T, and high vacuum. The one-of-a-kind combination of materials allows absolutely stable single quantum dot measurements at low temperatures over long periods of times, even when refilling the bath cryostat with liquid Helium. The adjustable transmission mode operation integrated in the instrument is absolutely unique in low temperature microscopy! Detector 3 L Laser Detector 1 Detector 2 (optional) Coupler 2 Illumination / Collection Fiber Vacuum Window Thin-Walled Stainless Steel Vacuum Tube COMPATIBLE COOLING SYSTEMS (see page 6) > LTSYS-He4 / LTSYS-He3 / LTSYS-HeDIL (on request) > LTSYS-Cc / LTSYS-CcADR / LTSYS-CcDIL PRODUCT KEY FEATURES > optimized for reflection and transmission experiments > highest stability enabling long term experiments > minimal light loss for highest sensitivity z-axis y-axis x-axis Low Temperature Compatible Objective Sample Scanner Superconducting Magnet (optional) x-axis y-axis Ultra Stable Titanium Housing attocube systems Positioning Stages EXAMPLE APPLICATIONS z-axis Liquid He Dewar He > absorption, scattering and fluorescence properties, (optional) investigation of complex nanostructures, single molecules, liquid He and quantum dots > low coherence tomography > single molecule life-time measurements Schematic drawing of the confocal setup attocfm III. attocube systems explore your nanoworld

16 PAGE 45 & PRODUCT CATALOG... Principle - The schematic drawing to the left illustrates the attocfm III confocal microscope. A laser beam is coupled on the first arm of a 50/50 single mode optical fiber coupler. The fiber end of the second arm is placed in a ceramic ferrule. This single mode fiber illuminates the sample and plays the role of the blocking pinhole aperture when collecting the scattered reflected light from the sample. The intensity of this scattered light is measured by a detector connected to the fourth arm of the fiber coupler (Detector 1). The second detector is used to monitor the laser source. A second confocal objective is used for transmission measurements. The transmitted light is measured by Detector 3. Objective Systems - Three different objectives are available as described in the section low temperature objectives. An increase of the numerical aperture by a half ball sapphire lens is possible, thus leading to an increase in resolution to nm (with red laser light illumination). Reflection (top) and transmission (bottom) image of Cr on SiO 2 grating with a period of 10 µm recorded with the attocfm III. (attocube application labs 2005). The attocfm III microscope module. nanoscopy Scanning Probe Microscopes for Extreme Environments

17 PAGE 46 & PRODUCT CATALOG Specifications attocfm III Complete System Confiiguration For Low Temperature SPM NANOPOSITIONING Ultra-Compact Positioners for extreme Environments NANOSCOPY Scanning Probe Microscopes for extreme Environments attocontrol SPM-Controller Soft- and Hardware attooptions Options for Positioning and Microscopy Contact attocube s sales engineers for complete system configurations: attocube systems explore your nanoworld

18 PAGE 47 & PRODUCT CATALOG attocfm III The attocfm III microscope module. nanoscopy Scanning Probe Microscopes for Extreme Environments

19 PAGE 48 & PRODUCT CATALOG Low Temperature Objectives for attocfm II and attocfm III :... attocube systems offers several low temperature compatible objectives in combination with the scanning confocal systems attocfm II and attocfm III. Dependent on your experimental requirements, wavelength range, working distance, and other parameters can be adjusted. For customized solutions, please contact our office. Systems A-C: standard configuration These objectives offer the highest achievable resolution. Optimized for wavelengths from 460 to 1550 nm. Ø 12 Focal plane 33.9 Working distance 2 4 Ø 5 Ferrule Fiber System D: achromatic configuration These objectives are achromatic over a wide spectral range. Different energy bands are available. Ø Ferrule Fiber Working distance M6 x 4 Focal plane ~ ~ ~ ~ attocube systems explore your nanoworld

20 PAGE 49 & PRODUCT CATALOG Low Temperature Objectives.... Confocal image of a chess board grating (SiO 2 on Si) with a period of 2 μm, recorded in reflection mode and step scanning with ANPxyz100 positioners. The sample has some defects on the surface structure which are clearly resolved. The image was recorded with the attocfm I in reflection mode. (attocube application labs, 2004). nanoscopy Scanning Probe Microscopes for Extreme Environments