Introduction. Manufacturing process flow for micro plastic lenses. Lens Design. Mold Making. Mold Design. Injection. Measurement. Coating.

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1 Application note A150: Smart phone lens mold LuphoScan (3D non-contact) Fast highly accurate metrology tool for smart phone lens mold characterization Yang Yu, PhD Senior Applications Scientist, Gernot Berger, PhD Business Development Manager The manufacture of micro-optic lenses for the mobile phone industry continues to grow with the increased use of smartphones. The mass production of micro-optic lenses has become easier than ever, particularly since the introduction of molding techniques for glass lenses injection molding methods for the popular plastic lens. The ease in making aspheric other structured lenses makes automated production of these lenses possible, significantly reduces the lens production time. In addition, to the use of plastic injection or glass molding techniques, advanced coating technology has greatly reduced mass production costs. Manufacturing process flow for micro plastic lenses Lens Design Mold Design Mold Making Injection Package Quality control Measurement Coating Taylor Hobson 2016

2 Application note A150: Smart phone lens mold 2 Importance of the lens mold its key parameters Quality control of lens molds is very important for lens development production, particularly for the popular plastic lens, whose quality is mainly depends on the lens mold. Precise of the camera lens mold is becoming more challenging for metrologists seeking to optimise the complete process chain in an industrial environment. This is because the slope of lens surfaces is getting steeper (up to ~65 or more), their size is getting smaller (down to ~1mm), tolerances are getting tighter in the lens mold industry. The common type of lens mold used in most industries is an aspheric shape. Aspheric form error the absolute position error to the peripheral rim/mold mounting shafts are important parameters because they are directly reflected in the quality of the lens products. These factors affect the focus quality, therefore reduce the optical efficiency. Measurement techniques Due to the requirements of the mobile phone lens mold industry a fast, accurate 3D non-contact technique with large slope capability flexibility is desired. Contact techniques are used by most lens mold industries for quality control of the lens mold. These kinds of lack flexibility for checking relationships between the axes, such as the absolute position error of the aspheric lens mold to its peripheral rim/shafts. Non-contact techniques such as CSI (coherence scanning interferometry), are not suitable for smart phone lens mold, due to the limitations of slope for the objective lens. For scanning confocal microscopy, although the surface slope capability is much improved in comparison to CSI; its limited vertical range, long time inability to measure lens off-axis error excludes it from smart phone lens mold applications. Smart phones Lens mold manufacturing Smart phone lenses Taylor Hobson 2016

3 Application note A150: Smart phone lens mold 3 Advanced optical metrology tool for lens mold (LuphoScan platform) - Multi-Wavelength Interferometry (MWLI) The LuphoScan platform is a patented interferometric scanning metrology system based on multiwavelength interferometry (MWLI). The systems are designed to perform precise non-contact 3D form s, mainly of rotationally symmetric surfaces such as aspheric lenses. The system is based on a combination of scanning four-axis geometry a non-contact interferometric (MWLI) probe. The basic principle for measuring the 3D form error of spherical, aspheric or other rotational objects, is that the probe is guided in a programmed curve over the surface of the object such that the distance between the probe the object is kept constant the probe is always presented perpendicular to the surface of the object. The absolute capability of the MWLI sensor technology makes its function flexible, even catering for surface s such as segmented objects as it allows for interrupted beams. Benefits of LuphoScan Non-contact 3D Super-fast High accuracy Function flexible The scanning process is accomplished by means of a MWLI point sensor, its position being controlled by 2 precise linear stages 1 precise rotary stage. The MWLI point sensor continuously measures the distance to the object surface by following a programmed curve, while the object is rotated on a high precision air bearing spindle, so as to perform a spiral scan over the whole surface. As a result real 3D topography can be obtained quickly (normally in a few minutes) to reveal the true surface form error from the designed shape the defects of the object surface. Taylor Hobson 2016

4 Application note A150: Smart phone lens mold 4 LuphoScan platform - Multi-Wavelength Interferometry (MWLI) Metrology frame 4 axis geometry: -- 2 linear roller bearing stages (R, Z positioning of the probe) -- 1 rotational roller bearing stage (T tilt of the probe) -- 1 rotational air bearing stage (C rotation of the object) Independent metrology frame to compensate for axial errors in the principal plane 3 reference probes determine the position of the object probe within the reference frame Temperature compensation Two linear reference stages One rotary reference stage Object probe Object C-axis Scanning point Spiral scan Probe presented normal, equidistant to the surface Probe follows the designed curve while measuring the distance to the object surface Non-contact 3D topography for rotational parts Applications optimized for rotationally symmetric parts; can also hle some complex shapes like axicon, segmented, annular asphero-diffractive lenses slight free form parts Form accuracy ± 50 nm (2σ) over the whole range Absolute flexible functions Measurement range ~1.0 mm to ~ 420 mm (diameter) Maximum slope up to 90 for convex lens 65 for concave lens Materials capable of measuring various materials surface finishes Taylor Hobson 2016

5 Application note A150: Smart phone lens mold 5 Case study In this note, the method of a LuphoScan system is illustrated using an example of a very small lens mold. Characterisation of smart phone camera lens mold A typical concave aspheric camera lens mold was tested using a LuphoScan system, with a 2.4 mm clear aperture, 0.5 mm sag 55 deg maximum slope. The tests were carried out by applying the Interlignment Module in LuphoScan software. The form error of the aspheric optical surface its absolute correlation to the mold rim mountings were measured. In addition, its tilt decenter error (off-axis error) with respect to the selected mold mounting shaft axis can also be determined in the same software module. Procedures Measurement of the aspheric optical surface form. Position error s of the aspheric optical surface to the user defined reference ring/shafts a. Measure tilt error with the user defined reference rim along with its height with respect to the optical surface form axis b. Measure decenter (with plane A) c. Measure decenter (with plane B) Interface of Interlignment Module Measure decenter (plane A) Taylor Hobson 2016

6 Application note A150: Smart phone lens mold 6 Measurement process of a cell phone lens mold Measure the aspheric optical surface Measure tilt error height with the user defined reference rim User defined reference plane A User defined reference plane B Notes - the reference ring/planes axes for calculating the position errors including the decenter errors tilt errors, can be defined freely by the user such as roundness planes or 3D cylindrical sections Taylor Hobson 2016

7 Application note A150: Smart phone lens mold 7 Example of results from a lens mold Aspheric optical surface form results Position error results Taylor Hobson 2016

8 8 Application note A150: Smart phone lens mold All the s were completed automatically in one cycle, without operator intervention. The user only needs to type in the aspheric designed parameters once select the desired reference rim/planes or 3D cylinders before the s. The lens mold form was completed in about 3 minutes, the position error s were done in 3 minutes. All the required results, such as form error position errors, can be displayed at the end of the. Summary A LuphoScan system combines the advantages of high precision non-contact 3D profilometry, large slope capabilities. It is a fast, non-destructive, precise function flexible 3D noncontact metrology tool. Accurate 3D topography of the lens mold its position errors can be obtained automatically within a few minutes. LuphoScan systems can greatly help the lens mold manufacturer to improve the optical surface of a lens mold its position relative to the mold rim mold mounting shafts. Some other relevant application notes A139 High precision of steep-sided miniature aspheres Application note A139: Steep-sided miniature aspheres PGI Dimension aspheres High precision of steep-sided miniature aspheres A140 Advanced contact non-contact metrology for characterisation of optical lenses Lucy Cooper, Applications Engineer A manufacturer of steepsided molded lenses had serious yield problems with lenses molds, which were difficult to manufacture due to the steep slopes tight tolerances involved. PGI Dimension helped to improve their process control manufacture, increasing yields by over 10%. Erik Stover, Business Development Manager, Taylor Hobson Challenges Steep-sided miniature aspheres are found in many Steep-sided aspheric molds for small optics are applications such as blu-ray stard DVD among the most deming of today s ultra-high optics, cell phone camera lenses, digital camera Application precision form note A140:applications Optical lenses lenses, high power LEDs fibre coupling present a number of challenges in obtaining highly optics. Obtaining highly accurate repeatable accurate repeatable data. s of the molds that produce these PGI CCI contact non-contact techniques 1. Steep sides There are two fundamental steep-sided miniature aspheres is critical for both issues here, the first is to avoid any stylus flanking design improvement manufacturing process at all as this totally invalidates the data set (see control. Figure 3a). Secondly, even if flanking is overcome In this application note we identify some of by a special stylus, many systems the challenges faced by profile will show a progressive deterioration in data measuring instruments explain how Taylor quality as the slope gets steeper. Hobson s PGI Dimension addresses these by providing high quality multi-profile data 3D 2. Alignment The measuring instrument needs astigmatism analysis. an alignment capability that ensures that each is taken right over the aspheric Yu, PhD; Richard Smith Figure 1: Measuring a steep-sided miniature asphere Yang axis. Simply measuring over an ill-defined turning point on an asphere will yield poor results. The sample s aspheric axis must be truly aligned withapplication note A140: Optical lenses lenses required by an optical system greatly Traditional spherical optics become heavier the instrument s rotational axis. This is particularly minimised chromatic spherical aberration larger as lenses are combined to achieve important if profiles are taken at different angular PGIerrors by CCI contact non-contact techniques means of compensation techniques: an increase in functionality precision, positions. A taken even a few diffractive zones can be adopted to compensate but in recent years modern optical designs microns off axis, or where the sample is tilted for chromatic aberration arising from the have employed aspheric diffractive optics even slightly, can result in significant refractive properties of the lens. to reduce the number of lenses needed: errors. It is therefore critical that the instrument one aspheric or diffractive lens can replace alignment process isspherical repeatable wellas defined Key parameters lens form several conventional lenses a the that weight, the instrument highused inherent result cost has space are all roughness accuracy stability. Thecompact smaller the reduced, achieving a more sample better Lens form is one of the most important optical the steeper sides the more critical this performing optical the system. design parameters used to control the quality of Figure 2: Common applications of steep-sided becomes. precision aspheric asphero-diffractive optics, miniature aspheres Diffractive lenses are normally used by optical 3. Measurement repeatability As discussed, ensuring they perform as required. In addition, designers to correct for chromatic aberration Yang Yu, PhD; Richardaffects Smithperformance. It is surface roughness sample is necessary reliable aspheric opticsalignment can be used to reducebefore or repeatable s be made. As we therefore essential to use the very best most eliminate spherical aberration,can thereby improving efficient techniques. arequality. dealingdiffractive with such optics small samples focus provide newlow note A142: Steep-sided small hemispheres tolerances this presents a significant challenge lenses required by anapplication optical system greatly spherical optics become heavier powerful degrees of freedom for lens design Traditional In this application note we provide some minimised chromatic spherical aberration inrequires the system to be larger as lenses are combined to achieve result high quality data from optical systems. examples of the of aspheric PGI Dimension Hemispheres errors by means of compensation techniques: highly capable highly stable. Instrument set-up, an asphero-diffractive increase in functionality precision, lenses using both contact More recently, the of asphero-diffractive environment use alignment are very important but(pgi) in recent years modern optical designs we diffractive zones can be adopted to compensate non-contact (CCI) metrology for chromatic aberration arising from the lenses has significantly reduced the number of have employed aspheric diffractive optics factors. proceed with an introduction to each technique. refractive properties of the lens. to reduce the number of lenses needed: one aspheric or diffractive lens can replace Typical applications Key parameters lens form several conventional spherical lenses as a result the weight, cost space used are all Mobile phone cameras roughness Advanced metrology for optics Taylor Hobson 2013 reduced, achieving a more compact better DVD read/write heads Lens form is one of the most important optical optical system. With the rapid evolution of optics, suitableperforming advanced metrology tools are necessary Bar-code scanners design parameters used to control the quality of for characterizing lenses with more complex shapes, of various sizes made of High power LED optics precision aspheric asphero-diffractive optics, normallytoused by optical different materials. A number of metrologydiffractive tools havelenses beenare employed measure the ensuring they perform as required. In addition, Blu-Ray DVD optics correctstylus for chromatic aberration aspheric asphero-diffractive lenses. Fordesigners instance,tocontact profilometry surface roughness affects performance. It is Cameras Lucy Cooper, Applications Engineer non-contact interferometry techniques. aspheric optics can be used to reduce or Projectors eliminate spherical aberration, thereby improving therefore essential to use the very best most efficient techniques. Automotive medical Phase Grating Interferometry (PGI) is a contact stylus profilometry, offer new larger focus quality. Diffractivewhich opticscan provide The main challenges are: Application note A143: New software to reduce set-up time for grinding diamond turning Head-up displays (HUD) gauge range to resolution when compared with other degrees tradionalofprofilometers, suchdesign as powerful freedom for lens In this application note we provide some inductive gauges laser interferometers. Coherence Interferometry (CCI) Taylor has designed In examples order to have in a of Infra-red thermal imaging Sample has steep sides There are two result in highcorrelation quality datahobson from optical systems. of theconfidence aspheric instruments provide advanced 3-dimensional non-contact surface characterization. The it is essentiallenses to achieve which PGI for rescue security X offsetissues compensation fundamental here, the first is to avoid any the PGI Dimension to meet process, asphero-diffractive using results both contact recently, the use of together asphero-diffractive technique is fast accurate provides amore high resolution 3D image with are(pgi) highly repeatable (CCI) also traceable Astronomy non-contact metrologyto we stylus flanking at all as this totally invalidates the ever-increasing demsof significantly reduced the number analysis that includes 3D roughness, 3D formlenses analysishas 2Dthe profile s. international stards. Spectroscopy proceed with an introduction to each technique. data set. of modern optics applications. Optical communications In this Application Note, a traceable calibrated Secondly, even if flanking is overcome by a Biomedics Typical applications Bob Bennett, Technical stard is measured on Taylor Hobson s PGI special stylus, many systems will Director, Taylor Hobson Ltd. Dimension in order to demonstrate system Mobile phone cameras Advanced metrology for optics show a progressive deterioration in data quality Taylor Hobson 2013 accuracy, repeatability the capability of DVD read/write heads as the slope gets steeper. up to 85 degrees slope. With the rapid evolution of optics, suitablemeasuring advanced metrology tools are necessary Bar-code scanners for characterizing lenses with more complex shapes, of various sizes made of We also identify some of the High power LED optics Alignment The measuring instrument needs different materials. A number of metrologychallenges tools havefaced beenwhen employed to measure the measuring steep sided Blu-Ray DVD optics an alignment capability that ensures that each aspheric asphero-diffractive lenses. Forsamples instance,oncontact stylus profilometry a profilometer explain how Cameras is taken right over the sample non-contact interferometry techniques. Cooper, Applications Engineer Taylor Hobson s PGI Dimension addresses theselucy Projectors centre. Simply measuring over an ill-defined stylus provides high quality multi-profile data. Automotive medical Phase Grating Interferometry (PGI) is a contact profilometry, which can offer larger turning point may yield poor results. The Application note A144: Camera lenses Head-up displays (HUD) gauge range to resolution when compared with other tradional profilometers, such as sample must be well aligned to the instrument s Survey Challenges inductive gauges laser interferometers. Coherence Correlation Interferometry (CCI) Infra-red thermal imaging rotational axis. This is particularly important if instruments provide advanced 3-dimensional Small non-contact surface characterization. Themost for rescue security Diamond is often used toangular manufacture diamond turning customers in America PGITen Dimension traceability The AAU the software diameter optics arenew amongst profilesturning are taken at different positions technique is fast accurate provides a deming high resolution 3D image togetherprecision with quality elements taken used inoff axis may were approached with a survey to determine Astronomy of today s ultra-high form highare taken.aspheric A from Taylor Hobson has analysis that includes 3D roughness, 3D form analysis 2D profile s. optical assemblies in telescopes, lasers, videoit is the effect of Taylor Hobson s X-offset radius Spectroscopy radius applications. They result in significant errors. increased our capability to projectors numerous other systems error compensation capabilities. The average Optical communications present a number of challenges in obtaining therefore critical that the instrument alignment manufacture Diamond turning is a multi-stage savings on set-up time are 330 hours per year. Biomedics highly accurate repeatablehigh data.accuracy A traceabledevices. process is repeatable well defined In the final stages of the manufacturing The larger benefit will be the scrap / rework opticsway with hemispherical stard isinfrared an excellent of process. that the instrument has high inherent accuracy a diamond tipped lathe tool is used to reduction due to the X-offset compensation Taylor Hobson 2013 process, proving the process capability. enhanced diffractive stability. The smaller sample achieve sub-nanometre levelthe surface finishes for the effects of the temperature drift in the steeper the sides the more critical this analysis capabilities. the sub-micron form accuracies. diamond turning process. becomes. Tim Olsen (Dir. Of Engineering) Janos Measurement repeatability As discussed, reliable sample alignment is necessary beforejunji Kumasa, Asia Applications Manager Technology repeatable s can be made. As we are dealing with small samples low tolerances this presents a significant challenge Coherence Correlation Interferometry (CCI) requires the system be highly The PGI Dimension has Ultra-high precision optical systems capable highly stable. Instrument set up,components require of subgiven us much improved environment alignment are very important micron form accuracy nanometric surface factors. capability to measure a very finish in order to meet the stringent dems of Advanced contact non-contact metrology for characterisation of optical lenses A141 Unique capability for steep-sided miniature hemispheres Advanced contact non-contact metrology for characterisation of optical lenses A142 Unique capability for steep-sded small hemispheres Unique capability for steep-sided small hemispheres A143 New software to reduce set-up time for grinding diamond turning New software to reduce set-up time for grinding diamond turning Figure 1: METAS Certificate of Calibration No Mean Diameter mm large range of optics from Application note A148: Small optics A148 A dvanced metrology solutions for small optics Advanced metrology solutions for small optics modern optical technology. Figure 2: The fast tool Servo system enables By use a high precision Referencesuch the of diamond turning ofcalibration surface structures diameter diffractives 2013Stard, Taylor Hobson thisprisms, application shows how Taylor Recent developments at Taylor Hobson have led as micro lens note arrays, torics off-axis aspheres. The to the availability of a gull newwing Aspheric Analysis UtilityHobson s PGIwith Dimension provides aspheres departures upsenior todefinitive 1000 microns Scientist Yang Yu, PhD. Applications (AAU) software Dimension package. Thisalso not has only aprovides very assessment of radius accuracy form error. the form error of aspheres diffractives, but impressive accuracy also calculates the X-offset tool radius error robust performance, giving which are common frequent problems in the Validation traceability cameras, photolithographic alignment With the increased requirements of us results we can trust diamond turning process. To help validate thereducing PGI Dimension systems laser surgery. Small Fresnel size absolute weight for many analysis reliability we can leadingmicro-optic class In addition to this X-offset feature, Tayloraccuracy, Taylor Hobson lenses are typically used in mobile opticaluse devices, lenses count on day after day. R12.5 mmspherical calibration Hobson Precitech have developed software accuracy R22.5 mmincluding phone cameras, other different types small lenses, balls (Figure 2) provided by lenses the Swiss that enables the machine metrology to of illumination. Small artificial IOL aspheric Federal lenses with Yann Guimond communicate with each other. This enables Institute of Metrology (METAS). Radiussuch as small (Intraocular lens) lenses are implanted structured surfaces; automatic correction of thegeneral X-offset Manager tool uncertainty of these calibration balls is within inside the eyes to correct focusing diffractive lenses, Fresnel lenses GLASS in 50 nm calibration radius errors, providing UMICORE a significant IR reduction is carriedlenses; out by errors for cataract patients to regain intraocular area micro getting more set-up time improved process performance. CMM. their vision. more popular. These micro-lenses have a wide range of applications. For Micro lenses, whether with structured Taylor Hobson 2013 example, small collimation lens forfig. 1: METAS certificate of calibration ball optical fibre, micro-diffractive lenses are surfaces or without, provide very challenging topics for designers, used for vision correction, colour laser Fig. 2: R22.5 mmprojection R12.5displays, mm light-weight low lost manufacturers metrologists. smallturning steep spheres Figure 1: Diamond machine to large A144 Definitive assessment of radius accuracy form error for steep moulds moulds Definitive assessment of radius accuracy form error for steep moulds Some traditional techniques such as stylus contact profilometry are no longer suitable for the of these microlenses, due to possible soft or fragile surfaces. There are also complicated factors, such as high aspect ratio structures for some diffractive lenses, arising from the small size of the components high contact pressure of the stylus. Advanced non-contact metrology tools are urgently needed to control the quality of micro optics. calibration balls infrared imaging, mobile phone Cell-phone CCI provides Form error Roughness Step heights Derived coefficients conic constants Base radius Defects Taylor Hobson 2013 Intraocular lens Laser collimation DiskArt 1988 Optical lens Taylor Hobson 2015 Taylor Hobson UK (Global Headquarters) PO Box 36, 2 New Star Road Leicester, LE4 9JD, Engl Taylor Hobson France Taylor Hobson Korea Tel: taylor-hobson.france@ametek.com Tel: taylor-hobson.korea@ametek.com Tel: taylor-hobson.sales@ametek.com Taylor Hobson Germany Taylor Hobson Mexico Tel: taylor-hobson.germany@ametek.com Tel: taylor-hobson.mexico@ametek.com Taylor Hobson India Taylor Hobson Singapore Tel: taylor-hobson.india@ametek.com Tel: Ext 120 taylor-hobson.singapore@ametek.com Tel: Taylor Hobson Italy Taylor Hobson Taiwan Chengdu Office Tel: Tel: taylor-hobson.italy@ametek.com Tel: taylor-hobson.taiwan@ametek.com Guangzhou Office Taylor Hobson Japan Taylor Hobson USA Taylor Hobson China Shanghai Office Tel: Beijing Office Tel: taylor-hobson-china.sales@ametek.com.cn Tel: taylor-hobson.japan@ametek.com Tel: taylor-hobson.usa@ametek.com Taylor Hobson 2016