This PDF file contains the front matter associated with SPIE Proceedings Volume 12221, including the Title Page, Copyright information, Table of Contents, and Conference Committee Page.

After two decades of development, the James Webb Space Telescope launched on December 25th, 2021. This revolutionary telescope is the first ever 6.5 meter segmented telescope in space that was the work of 1000’s of engineers, technicians and scientists. Once in space, there were over 50 successful deployments followed by the first ever alignment of a segmented telescope in space and instrument commissioning. This talk will review the history of the telescope development through testing and on-orbit commissioning with a special focus on the optical technologies that both enabled the observatory and that were proven out through the commissioning.

We present our technology supply chain for the prototyping, replication and metrology of freeform (micro-)optics. We show through recent examples how this technology supply chain is a key-enabler for frontier applied research and demonstrate how it paves the way towards efficient technology take-up and effective industrial innovation.

NASA's Exo-S Starshade Mission plans to spectroscopically characterize exo-Earths orbiting stars in their "Goldilocks Zone" using an occulter (the "Starshade") to suppress starlight by 10^10. LUVOIR, HabEx and other missions may also depend on starshades. Other missions, such as LISA, critically depend on complete elimination of light scatter, as does the terrestrial LIGO. We report data on a family of novel, peelable, low-adhesion, residueless polymer coatings to clean and protect Starshade edges and other surfaces of importance to NASA, with uses ranging from fabrication to integration and testing to launch.

Ultrafast laser stress figuring (ULSF) currently allows for the figuring of large aspect ratio fused silica mirrors with an accuracy of <20 nm RMS over 6 orders of Zernike polynomials. While similar technologies are capable of this accuracy, ULSF has the potential to be orders of magnitude faster. ULSF is an iterative process in which (1) an optic is figured, (2) optical metrology is used to measure the surface figure, and that measurement is used as feedback to repeat this closed-loop process and further figure the mirror until the mirror has reached the desired figure. We present an in-situ, on-machine optical metrology system that measures the mirror surface figure using differential phase measuring deflectometry (DPMD). After an absolute measurement of the surface figure is done using interferometry prior to any figuring, our differential deflectometry system can measure the change in surface figure after each laser stress figuring process. This eliminates the need to remove the mirror from its mounting, which can induce non-repeatable surface figure errors during the metrology step. The differential deflectometry system is also used to calibrate the ULSF process prior to the figuring of the mirror. We utilize and characterize the in-situ differential deflectometry system during the surface figuring of a 25.4 mm fused silica mirror and summarize the results in this proceeding.

The decrease of transmittance due to electromagnetic radiation is called solarization. UV radiation generates color-centers in the glass that act as absorption sites. The spectral characteristic and level of solarization depends mainly on the composition. In microlithography applications optical glasses are used that are optimized for UV irradiations at 365 nm with minimized solarization effects. The solarization behavior of optical glass at SCHOTT is usually characterized using a Philips mercury high-pressure gas-discharge lamp type HOK-4/120 or a 365 nm LED. A method for solarization classification is described in the Japanese JOGIS standard 04-2019. Results are shown and discussed in comparison for several UV transmitting optical glasses and glasses used in i-line lithography applications. In recent years blue laser applications became more and more present in industrial and commercial applications. It was surprisingly found that high power blue laser irradiation also leads to solarization of optical glass. Therefore SCHOTT established a blue laser irradiation setup and spectral photometer measurement facility to characterize blue laser solarization effects on optical glass. Additionally stabilization strategies have been applied to stabilize optical glass against blue laser solarization. This paper discusses the actual status of the developments.

The International drawing standard, ISO 10110, is gaining momentum globally, enabling a broader accessibility between designers and fabricators. Additional ISO standards for optics and photonics are available for requirements beyond the basic notation used for specifying optical element properties and dimensions. For example, a designer will also want to specify environmental conditions for optical coatings or conditions for the entire optical system. The notation used for these requirements are not included in the ISO 10110 series, but they follow a similar coded notation. Specifying these tests may be an additional advantage for many companies in the United States who wish to utilize ISO 10110 for their drawings. Understanding how to specify these tests allows a smooth transition in moving from drawings typically specified in the classic ASME/ANSI Y14.18M standard to a single international standard system.

There are numerous challenges associated with safely handling today’s photonic devices. These devices tend to be very sensitive to surface defects including scratching, foreign particles, and residue, all of which can be detrimental to their end-use performance. To address these concerns, industry requirements for handling optics and photonic devices are becoming more stringent with an increasing need for carriers that limit or avoid contact with the device active area. The limitations of traditional component handling technologies led Gel-Pak to investigate bio-based adhesion and to understand how its gripping action works. The presentation will discuss a body of work that has been published in this field studying how geckos, lizards, beetles, spiders, and ants can attach themselves to different surfaces but also detach themselves very easily without disturbing the surface. The research points to a unique micro-texture commonly found on the toe pads of such animals. Inspired by Gecko fibril microstructures, Gel-Pak has developed a series of textured carriers with reversible adhesion which limit the surface contact to less than 2% of the device surface area or entirely exclude any contact to the active device surface. These carriers are well suited for handling fragile optics and photonic devices. The presentation will discuss the specifics on this development effort and performance.

We describe progress on the Nautilus Space Observatory concept that is enabled by novel, very large (8.5mdiameter), ultralight-weight, multi-order diffractive lenses that can be cost-effectively replicated. The scientific goal of Nautilus is the rigorous statistical exploration of one thousand potentially life-bearing planets and the assessment of the diversity of exo-earths. Here we review the science requirements and key design features of Nautilus. The new optical technology (MODE lenses) at the heart of the Nautilus telescopes also poses exciting new optical fabrication and metrology challenges. We will summarize these challenges and provide an overview of emerging solutions.

The longitudinal chromatic aberration (LCA) specific to a high-harmonic multi order diffractive engineered (MODE) lens designed for the astronomical R band (589nm to 727nm) is described and demonstrated. This Type 2 LCA is characterized by rapid changes of focal position versus wavelength over a focal range of f0/M, where f0 is the design focal length at 658nm and M=2196 is the harmonic order. Type 2 LCA effects on image performance and correction methods are also discussed and demonstrated.

The color corrector (CC) system serves as an essential part of the multi-order diffractive engineered (MODE) lens system to provide near diffraction limited performance by correcting residual refractive and diffractive dispersion of MODE primary over the astronomical R-band (589 nm to 727 nm). The CC is designed to collimate and refocus the image from the MODE primary as a unit magnification relay and corrects chromatic aberrations at the same time. As a result, the system including the optomechanics of the CC is specifically designed for compensating errors from both the MODE primary and the CC. Results regarding prototyping, assembly and testing of the color corrector are reported.

The stray light analysis and testing of multiple-order-diffraction engineered (MODE) lens telescope is an essential step in the evaluation of optical imaging performance of the telescope. The MODE primary lens has a multi-order diffractive (MOD) front surface and single-order (M = 1) diffractive Fresnel lens (DFL) rear surface. Both of MOD and DFL surfaces have four transitions between five annular zones. Stray light can be minimized to prevent unwanted photons from reaching the science instrument detectors. Stray light is evaluated on an optical testbed to test the polychromatic performance with a supercontinuum laser.

The primary lens of our multi-order diffractive engineered (MODE) lens telescope combines traditional lens design and a diffractive element to mitigate longitudinal chromatic aberration (LCA). This design uses a 24 cm diameter aperture. In order to make the primary in molded glass, the lens is constructed in 9 segments, 1 radially symmetric center segment, and 8 identical ring segments. A monolithic 24cm aperture MODE lens is not possible at this time, due to limitations of our 14 cm diameter molding cavity. The ring segments each subtend a 45° angular subtense of the ring around the center segment, combining to form a 360° ring around the center segment. Due to the irregular shape of the ring segments and the high precision diffractive surfaces within the design, the lenses are fabricated using precision glass molding (PGM). This presentation considers mold insert design, preform selection, and molding process development. Beyond the overall structure of the molds, the design of the mold insert requires considerations for thermal expansion of the mold and mitigation of adhesion between the mold and the lens using an antiadhesion coating. The preform selection considers both the thermal and optical properties of the glass to be molded and the proper shape of the preform for the easiest material flow during the mold cycle. The general molding process is summarized as heating the preform above the glass transition temperature, applying a force to the mold inserts, and cooling the mold assembly before release.

To meet the scientific requirements demanded for futuristic space exploration, the Nautilus space mission has adopted the newly developed multi-order diffractive optical elements (MODE) design. Primary optics with large aperture diameters, like those used commonly in observatories, are frequently the design most employed and demanded by astronomers. However, this is limited by the difficult challenges that comes with fabrication, alignment, and launch of said optics. The proposed primary optics fabrication breaks through these challenges by using molded segments as its primary optics. With the main advantage of requiring a relatively simplified assembly process and having a compressed volume, the compact form factor will allow for multiple telescope units to be sent together in a single launch. Additionally, the molding and segmented manufacturing creates a fine structure on the diffractive lens surface that is not easy to obtain via traditional surface removal fabrication processes for an identical optical surface piece. The feasibility of this assembly in respect to its accuracy and labor are the key factors of this approach. Therefore, we developed an in-Progress Metrology Control (iPMC) technique that was combined with a motorized mounting system to give us full autonomous closed-loop control during the UV curing of multiple segments. The iPMC monitors and guides the aligning of the adhesion process of the multi-segment MODE, while the metrology system measures the position of the multi-segments so that an individual actuator can automatically adjust the segment’s orientation during the UV curing process. This is happening simultaneously as the influence matrix of each actuator receives feedback from the metrology system. The validity of the iPMC is then checked using the mock-up MODE lens assembly.

The continued development of multi-order diffractive engineered (MODE) lens technology that utilizes both multi-order diffractive surfaces and a diffractive Fresnel lens surface1–3 allows for the conception and development of future applications of the technology such as lightweight large aperture telescope primary lenses. Manufacturing methods being developed for this technology use glass compression molding to create its unique optical surface features. However, to enable the design and development of larger apertures using the MODE lens, it is necessary to allow segmentation due to the size constraints of current glass molding technology. Previous proceedings presented the effectiveness of the Kinematically-Engaged Yoke System (KEYS) to align the segments of a 0.24-m, PMMA, monochromatic, MODE-like lens (having no diffractive Fresnel lens features). The KEYS alignment system consists of ball bearings with which the step-like features of MODE lens segments kinematically engage with. In previous iterations of the KEYS, these ball bearings were mounted on ultra-fine screws that are adjusted radially with flexures that occupy space in the transverse plane (perpendicular to the MODE lens’s optical axis). We present a new iteration of KEYS in which these radially adjusting flexures have been modified to be located in planes that contain the MODE len’s optical axis. The alignment and optical performance of the MODE lens are evaluated using deflectometry in order to determine its current resolution of lens segment adjustment. Improvement of the KEYS will allow optical performance testing of the aligned lens. This version of KEYS will be used to assemble a 0.24-m, compression molded, glass, segmented MODE lens.

The initial testing of prototype multiple-order-diffraction engineered (MODE) lens telescope is essential process before the sky test to evaluate the optical imaging performance of a space object. Prototype MODE lens telescope consists of MODE primary lens which is a core component to correct secondary spectrum, a field lens and a double Gauss type color corrector and achieves a diffraction limited performance. The performance is tested on the diffraction efficiency with respect to supercontinuum laser wavelength on an optical testbed and evaluated on the polychromatic performance for prototype molded ring segment.

A deflectometry simulation system for measuring and generating the surface profiles of freeform optical elements was designed. Unlike alternative optical metrology methods, deflectometry systems utilize the principle of pixel to pixel point mapping to measure a specular optical surface. The in-lab set up uses readily available materials such as an LCD monitor, a CMOS camera, and other basic lab items such as optical posts and post holders. A software that enlists the usage of phase unwrapping in order to derive the incident and reflected light vectors from a surface under test. These vectors provide slope information which can then be integrated into a surface reconstruction. This allows for a non-contact surface reconstruction method as well as a simulation to help calculate the best respective placements of monitor, camera, and test surface. This type of system is useful in a measuring more challenging optical surfaces such as free forms and convex optical surfaces. Disclosures of the system and distance sensing lasers could enable a very user friendly and intuitive handler experience for creating the surface reconstruction profiles with much more reliable system geometry information and reduction of excess light and scattering noise. Multi rotation stages can also be used for adjusting tip and tilt angles of test surfaces.

We propose the design of a conical null-screen with quasi-elliptical targets drawn on it so that its image, which is formed by reflection on a biconical convex surface, becomes a precise radial set of circular targets if the surface under test is perfect. This null-screen avoids alignment difficulties of the test system due to the contour of the face (eyebrows, nose or eyelids). In addition, the proposed method prevents the targets from overlapping and touching each other. We discuss how to integrate the system to calibrate it by testing a spherical and a biconical surface on which we obtain geometrical parameters such as radius of curvature and conic constant, as well as elevation, and sagittal and meridional curvature maps with a smartphone-based corneal topographer.

For any surface metrology system that obtains measurement with the aid of an imaging system, distortion must be carefully scrutinized. Both intrinsic lens distortion and perspective distortion embed surface error distributions that skew the interpretation of resultant surface maps. Either displaces acquired information due to the imaging process. Here, we quantify the origins of distortion, its modeling philosophy, and the effects of its digital correction procedure. This study includes simulation for lens-distorted systems such as interferometers and perspective-distorted systems such as monoscopic fringe projection profilometry and deflectometry. Summarily, this study hopes to clarify differences in low-order shape between surface metrology instrument measurements in which surface maps were not rectified for distortion.

Measurement of surface form after coating application is a vital final quality control step, but generally difficult using noncontact optical methods as the signal is distorted or drastically reduced by the coating. The NMF non-contact measurement machine range for freeform optics by Dutch United Instruments (DUI) can be employed for measurements during the entire production process. It can measure ground, polished and coated surfaces. Especially non-uniform coated surfaces may however distort the signal of the probe. A correction technique is described that allows for correcting this influence, enabling accurate non-contact form measurement after application of the coating.

It is well known that computer generated holograms enable standard interferometers to measure nearly any shape with accuracy of a few nanometers. Most high-precision non-spherical optical surfaces are manufactured based on CGH measurements. Historically, the application of CGH interferometry required a skilled optical engineer to define the test configuration, set up and align the hardware, and reduce the data. In this talk we discuss a different scenario, where the CGH vendor provides not only the hologram, but a kit of hardware and software that eliminates the need for a specialized engineer. The alignment is straightforward, the data acquisition follows the standard procedures for measuring spheres, and the data processing is automatic. Several examples illustrate this paradigm shift, including an autonomous system that loads the optics with a robot and performs snapshot measurements without any adjustment at all. This takes CGH interferometry from the laboratory to the manufacturing floor.

Absolute distance measurement technique can be a useful tool for solving the challenging issues such as large optics fabrication and alignment. An optical system free from non-measurable range of spectral-domain interferometer was proposed by using dual reference paths with orthogonal polarizations. The problem of non-measurable range caused by sampling limit of an interference spectrum having very small optical path difference has already been overcome by making the dual reference path with a pre-determined offset in the previous study. However, the interference signal between the two reference paths could cause the measurement error when it overlaps with the distance measurement signal. In this study, to remove the interference signal between the two reference paths, polarization-based spectral-domain interferometer was proposed and realized. For feasibility test of the proposed method, the absolute distances to the target mirror were measured within the scan range of 200 μm, and the measurement results were compared with those obtained using the commercial laser interferometer simultaneously. As a result, it was verified that the distance measurement error was significantly reduced through the proposed method.

We propose an optical system capable of simultaneously measuring physical thickness, group refractive index, and surface profile of a single-layer substrate based on a spectral domain interferometer. Specifically, the proposed method can be functionally divided into two parts; one is the Mach-Zehnder configuration for thickness and refractive index measurements, the other is the Michelson configuration for surface profile measurement. To integrate two different configurations into a single system, two fiber components of an optical circulator and a 2-by-1 optical coupler were installed for the purpose of acquiring both signals reflected from and transmitted through the sample. In addition, the Michelson configuration was realized by replacing a right-angle turning mirror with a beamsplitter and adding a reference mirror in the Mach-Zehnder layout. For feasibility test of the proposed method, a 100-mm-diameter silicon wafer was laterally scanned within a square area of 50 mm2 using a two-axis motorized linear stage. The reference mirror for surface profile measurement was suitably positioned along the optical axis to prevent the overlap between the optical path differences. As a result, the distribution maps of physical thickness, group refractive index, and surface profile were successfully measured over the target area of the silicon wafer. In the proposed setup, the measured surface profile of a plane-parallel substrate like a silicon wafer represents the bending information in its natural state. The proposed method is highly applicable to the semiconductor or display devices inspection where thickness and surface profile measurement should be monitored simultaneously.

Large Aperture Mirrors (LAMs) are essential for space telescopes and ground-based observatories. The need exists in characterization of multiple modality dynamics of recently developed LAM’s membrane mirror structure. Knowledge of this dynamics is essential to LAM’s design, balancing and operational efficacy of future systems. This presentation discusses the Whole-Field Laser Doppler Vibrometer (WF-LDV) - the newly developed instrument capable of instant characterization of LAM’s vibrational spectra and full dynamic of its membrane-like mirror surface. WF-LDV allows a picometer-scale accuracy in the multi-kHz frequency band. Innovative WF-LDV design supports measurements of multiple modalities of optical metrology tailored specifically for LAM design.

The Shack-Hartmann wavefront sensor has the potential to directly characterize the optical performance of a freeform part by measuring the wavefront transmitted or re ected by the part. However, the traditional Shack- Hartmann sensor's small dynamic range and aperture limit its applicability on strongly curved or extended freeform parts. The combination of a Shack-Hartmann sensor with a highly precise positioning system and a suitable registration algorithm can overcome these limitations. This paper presents an integrated and fully automated measurement system that is based on a scanning Shack-Hartmann sensor, demonstrates the enabled dynamic range extension, and presents measurement results obtained from a microscope objective with a numerical aperture of 0.65. The results show the capability of measuring a wavefront with an opening angle of ±80° and detecting an rms wavefront error of 0:28 λ.

This paper presents an evaluation of three developed parallel registration algorithms for the reconstruction of optical wavefronts. Two practical use cases are considered including high-quality optics generating (i) a plane and (ii) a divergent wavefront. The wavefronts are measured segment-by-segment with a scanning Shack-Hartmann sensor measurement system and are reconstructed by the algorithms. As a benchmark for the comparison of the registration performance, the well-established iterative closest point (ICP) algorithm is used. Results show that the developed registration algorithms attain a registration precision up to a factor of 10 better than the registration precision of the ICP algorithm.

Centration measurements of lenses usually require two measurements of the center of curvature, one for each side of a lens. For aspheres, the situation is more complex, because an aspherical surface defines a set of centers of curvature for each diameter of the aspherical surface. This makes the measurement and its interpretation more complex. We present three different methods to measure the inner centration of an asphere and discuss accuracies and practical aspects. One approach is the use of a Computer-Generated Hologram in combination with a Fizeau-type interferometer. The CGH is split into a ring area for testing the first side of the asphere and a central circular CGH which is optimized for testing the spherical backside of the lens at the same time. The Zernike coefficients of the two interferometric measurements can be used to back calculate the inner centration. The second approach is based on an optical profiler using multi-wavelength interferometry. It collects surface data from the first and the second surface after another, by turning the lens surfaces using an additional tooling where common fiducials for both sides enable a precise mechanical relation. A third option is also based on this optical profiler, enabling the measurement of the back-surface through the lens. We have applied all three methods for testing one specific asphere and compare and discuss the results we have obtained.

Approximate and rigorous methods are widely used to model light scattering from a surface. The boundary element method (BEM) is a rigorous model that accounts for polarisation and multiple scattering effects. BEM is suitable to model the scattered light from surfaces with complex geometries containing overhangs and re-entrant features. The Beckmann- Kirchhoff (BK) scattering model, which is an approximate model, can be used to predict the scattering behaviour of slowlyvarying surfaces. Although the approximate BK model cannot be applied to complex surface geometries that give rise to multiple scattering effects, it has been used to model the scattered field due to its fast and simple implementation. While many of the approximate models are restricted to surface features with relatively small height variations (typically less than half the wavelength of the incident light), the BK model can predict light scattering from surfaces with large height variations, as long as the surfaces are “locally flat” with small curvatures. Thus far, attempts have been made to determine the validity conditions for the BK model. The primary validity condition is that the radius of curvature of any surface irregularity should be significantly greater than the wavelength of the light. However, to have the most accurate results for the BK model, quantifying the validity conditions is critical. This work aims to quantify the validity conditions of the BK model according to different surface specifications, e.g., slope angles and curvatures. For this purpose, the scattered fields from various sinusoidal profiles are simulated using the BEM and the BK models and their differences are compared. The result shows that the BK model fails when there are high slope angles and large curvatures, and these conditions are quantified.

An optical method of determining the location of the apex of a corner reflector mounted in a steel ball, commonly referred to as a Spherically Mounted Retroreflector (SMR), relative to the center of the ball to the 1-2 μm level was previously described by us. The method used an autostigmatic microscope focused on the apex and viewed the reflected spot image as the SMR was rotated about a normal to its entrance aperture. This measurement determined the lateral offset of the apex and tipping the SMR while viewing the spot gave an indication of the axial displacement. A related questions arose recently, could the distance between two SMRs be determined to the same level of precision if the SMRs were rigidly mounted in a fixture so they could not be moved. We show the answer is yes assuming the stage moving the pair of SMRs has the required precision. As a SMR is scanned under the autostigmatic microscope the spot motion seen by the microscope is identical to that seen when scanning a spherical ball under the microscope and we have already shown that balls centers can be found to 1 μm precision using a 10x objective. We show experimentally that we can determine the distance between 2 SMRs by repeated measurements with the balls in different azimuthal orientations, and show that by taking into account the orientation, the distance between SMRs remains the same within experimental errors.

Freeform optics have the ability to be used in design to reduce optical system size and improve performance for asymmetric systems, but present new challenges for manufacturing, testing, and assembly compared to spherical or aspheric systems. We investigated the effects of alignment errors on freeform surfaces on both a surface and system level. We will show how different levels of departure, from mild to wild, can affect the magnitude of these errors, as well as discuss different ways to mitigate these errors in the manufacturing, testing, and assembly processes.

Gravity-sag (G-sag) for large space-based telescopes is a critical error budget element that must be taken in consideration. Absolute characterization of gravity sag provides necessary information when testing light weighted optics so that true optical performance can be determined. A method is presented for characterizing G-sag to obtain the 0-G optical surface.

We propose a scatterometry solution to the side wall angle measurement problem in high aspect ratios semiconductor structures such as through-silicon vias, deep holes, and deep trenches.

To minimize the artifacts in Point Spread Functions (PSFs) of space telescopes such as the 6 major spikes shown in the star image observed by the James Webb Space Telescope, which are caused by the primary mirror outer boundary and the gaps between segments, an alternative method to segmentize large circular telescope mirror is proposed. From the fact that the strong spikes are due to the parallel-ness of all linear boundary edges and gaps in the current hexagonal segmentation approach, the proposed segmentation methodology minimizes such parallel-ness. The proposed method comes with a set of formulas that can assist the design process including the systematic calculation of number of segments and the size of each segment to cover the entire mirror pupil area. Some example PSFs of a few possible segmented mirrors with the proposed formalism will be presented.

Silicon carbide’s material properties make it a desirable choice as a mirror substrate, particularly for space-based optical systems where thermal stability and low mass are critical. Mirror substrates made from silicon carbide (SiC) often have a small amount of porosity or surface features that make optical surfacing of the bare substrate challenging. To achieve the surface figure and roughness required for diffraction-limited performance at visible wavelengths, it is common to apply a thin layer, or cladding, of a similar material that has properties more conducive to optical surfacing. The introduction of another material, however, has the potential to change the surface figure over temperature, even with small differences in thermal expansion between the cladding and the substrate. This paper presents testing to characterize that effect on a SuperSiC®-SP mirror clad with chemical vapor deposited (CVD) silicon carbide produced by Entegris Specialty Materials. This mirror was fabricated for a two-axis gimbal-mounted scan mirror assembly, which has been developed for the QZSS-HP program. The QZSS-HP is a hosted payload (HP) on the Japanese Quasi-Zenith Satellite System (QZSS) and will be used for space domain awareness (SDA). Thermal expansion measurements and optical surface measurements performed at Massachusetts Institute of Technology Lincoln Laboratory (MIT LL) show that the difference in coefficient of thermal expansion (CTE) is on the order of 0.2 parts per million per degree C.

This conference presentation was prepared for the Optical Manufacturing and Testing XIV conference, Optics + Photonics, 2022.

One of the most important components of a wind turbine are the blades, the evaluation of their manufacturing quality and aerodynamic capabilities can be very costly, for this reason a 3D reconstruction by stereo vision is proposed. This technique consists of projecting a laser line in each face of the blade. Using a linear stage, two cameras will scan simultaneously, considering bidirectional disparities and feature correspondences between the two pictures. Two symmetric airfoils of the NACA 0012 family are evaluated. The expected precision is 0.1mm.

This conference presentation was prepared for the Optical Manufacturing and Testing XIV conference, Optics + Photonics, 2022.

In this work, we show the design of a conical null-screen for evaluating non-symmetric convex surfaces, such as toroidal and biconical convex surfaces. We propose a customized evaluation algorithm to compute the shape of the surface. The data obtained by our algorithm are fitted to a customized non-symmetric shape surface, considering orthogonal polynomials, to obtain the geometrical parameters such as the radius of curvature and the conic constant. The advantages and disadvantages of applying this algorithm to the quantitative test results are also presented.

The intraocular lens (IOL) industry is continuously evolving with more complex surface designs that require affordable and timely surface measurements of extended depth of focus (EDOF) and diffractive multifocal lenses. Current systems to measure grating profiles, such as AFM, SEM, or optical profilometers are expensive, need intensive training, and are sometimes destructive. Furthermore, the fields of view of these systems are typically limited, so measuring the full aperture of the lens requires repeated measures and stitching of the result. The system developed allows for quick profile measurements with easy to obtain equipment that will help examine and develop diffractive multifocal IOLs. This study integrates a 3D GelSight camera (GelSight, Inc, Waltham, Massachusetts), a stepper motor, and an Arduino board with driver board to automate the measurement of IOL gratings. The GelSight 1.0X camera has a height resolution of 1.0 μm and is provided with software that will be used to select and export data from areas of interest. Post processing will be required to analyze the data from the GelSight, but can be customized to the user’s needs. Using simple Arduino code and a stepper motor to move the camera onto the sample allows for a hands-free measurement technique that promotes accuracy and repeatability. Automation allows for beginners to quickly use the newly proposed system for many profile measurement applications with little setup time. The system will benefit the development of IOLs as a quick and easy check for the production process of these advanced lens designs.

Maskless lithography (ML2) with a scanning high-density spot array has been applied to pattern writing of flat panel displays (FPDs) and printed circuit boards (PCBs). In a ML2 system, spot array diagnostics is necessary to calibrate spot position deviations to achieve exposure pattern uniformity. However, it takes time for the diagnostic including the throughfocus spot profile measurement of a large number of spots (~ 1M spots). Therefore, a high throughput spot diagnostic system is required. We have proposed an alignment-free, high-throughput and cost-effective diagnostic technique with a scanning linear image sensor. Through-focus spot profiles were reconstructed with through-focus scanning signals and response functions of the image sensor pixels. This technique can realize a cost-effective on-machine spot diagnostic system compared to conventional micro-slit scanning systems. We have demonstrated this spot diagnostic with the proofof- concept system. We have confirmed the feasibility in measurements and achieved a lateral position variance of σ < 0.1 μm, (7% of spot size 1.5 μm), an axial position variance of σ < 0.2 μm, (2% of DOF 10 μm) and a telecentricity variance of σ < 1.0 mrad. These variances are then correlating with the level of positioning variances in the stage repeatability. In addition, we also have demonstrated an estimation of low-order wavefront aberrations with a focal spot profile. This onmachine laser spot diagnostic tool could contribute to improve the pattering quality and monitor the optical performance for various focus-spot laser processing systems.

A practical implementation of the dynamic point shifting method as a corneal topographer is presented. A quadrangular OLED´s prism setup allows to change the target at will. This device has several advantages over the traditional commercial topographers using static target as those based in Placido disk. The target is displayed on the OLED screens as an image, by changing the image it is possible to change the spots position, but also, different targets can be used, for instance; B&W positive or negative, different colored targets, with square or radial arrays of spots, among other possibilities. Results of measurements obtained with calibration spheres as well as the first report of the qualitative evaluation of a corneal surface of a human volunteer using this device are presented.