This PDF file contains the front matter associated with SPIE Proceedings Volume 11487, including the Title Page, Copyright information and Table of Contents.

There is a potential need for large (<500 mm diameter) conformal windows for use on air, space, and water craft. These windows need to fit the curvature of the vehicle, which results in extreme freeform geometries. “Extreme Freeforms” are a class of shapes that do not have rotational symmetry, must be polished using sub-aperture techniques, and whose deviation from a best-fit sphere is on the same order as the size of the part. This paper will discuss some of the challenges associated with manufacturing optics of this size and shape and how Optimax solved them. These challenges include: blank acquisition, a lack of viable commercially available polishing platforms for extreme freeform shapes, and metrology. A demonstrator optic was designed and manufactured from fused quartz. Final metrology data for both sides of the window will be shown and discussed.

Pressure is a relevant parameter in the polishing of components according to the Preston equation.^{1, 2} Preliminary investigations have shown that the pressure can vary with inclined position and different polishing pads. It is not constant with regard to its distribution in the contact area between polishing pad and glass surface. In this publication, the pressure distribution during the polishing of glass components is analyzed. For the measurement of the pressure distribution a pressure sensitive foil is used.

This paper shall discuss the results of progress made towards the manufacturing of Large Space Optics and Lasercom Telescopes conducted on two highly competed NASA Phase II projects. Mirror substrates were made using patent pending nanoceramic composite Silicon Carbide (SiC) materials via novel processes. NASA Phase II Contract #80NSSC18C0077 addressed the design and manufacturing of a 25-cm Pathfinder mirror substrate traceable SiC scalable to meter-class segments for a far-infrared surveyor (the Origins Space Telescope, OST). The technology also is intended to fill priority technology gaps for the LUVOIR Surveyor, and Habitable Exoplanet Observatory (HabEx). The second SBIR, NASA Phase II Contract # 80NSSC19C0138, addresses the manufacturing of an ultra-lightweight, ultrastable RoboSiC™ lasercom telescope. Laser Communications Telescopes are needed by multiple Jet Propulsion Laboratory and multiple NASA cost centers for Cislunar, Earth-Sun-L1 and L2, Deep-space and for Planetary Missions with Orbiter-Landers.

The present paper shows a way for a cost-effective, integrated measurement of the density p of polishing suspensions. It is based on the principle of measuring the turbidity of a solution on the basis of the light transmitted through it, and of calculating back to the density on the basis of the turbidity. The tool is suitable for monitoring polishing agents and for detecting when the density of the polishing slurry leaves the permissible parameter space and can perspectively enable the automated monitoring and adjustment of polishing suspensions. The tool is named after an Octopus. These animals have amazing abilities, for example they can copy the behaviour of other sea animals or act with a plan. Their tentacles each have their own brain and can perform biochemical analyses.

ZERODUR® provides ultimate dimensional stability in monolithic and homogeneous forms ready for the next-generation of requirements for ground and spaceborne mirrors. Already ZERODUR® is providing nearly 10^3 matching meter-class mirrors for ELT and is now the baseline optical material for NASA’s HabEx coronagraph 4-meter diameter lightweight mirror needing 10 picometer stability for 10^3 seconds. We will describe the utility to the optical designer of SCHOTT’s newly dedicated “world class” ZERODUR® competence center capable of machining and precisely characterizing monolithic lightweight mirrors through 4-meter sizes. This facility, and refined manufacturing methods, enable cost-critical missions to evoke design-to-cost paradigms. Both mirror designers and optical finishers can expect a better starting point via precision generation of any optical form on a mirror’s specular surface while minimizing sub-surface damage. Complimentary engineering studies will be discussed.

As on-machine metrology for freeform optics becomes increasingly popular, error analysis and compensation techniques and probe path optimization must evolve in response. For this work, a four axis Moore Nanotech Universal Measuring Machine (based on a diamond turning machine design) is used with a Precitec chromatic confocal probe. The system is set up in a thermally controlled enclosure, and a LabVIEW data acquisition program is used to record probe data, time, and machine positioning data directly from the machine scales. Issues addressed include probe testing and calibration, thermal errors, data age, compensation methods, and probe path optimization for error reduction. The combined error reduction/compensation approach improves on-machine metrology for freeform optics.

Continual development of optical testing methodologies for silicon photonic components and circuitry is instrumental for the overall growth of the field. A mature scheme capable of coupling light between the fiber core and single mode silicon-on-insulator (SOI) waveguides for wafer-scale testing are grating couplers. When silicon photonics are integrated into 3D architectures, the photonics layer may undergo multiple wafer flipping steps through bond/de-bond modules. Architectures such as this require optical testing on the front and backside of the wafer. Conventional grating couplers integrate reflective layers or additional layers of gratings to increase coupling efficiency. These techniques however will not work in both wafer orientations. In addition, including separate test structures for both front and backside fabrication increases device footprint and drives up manufacturing costs. We present an isotropic grating coupler that provides moderate coupling efficiency for both front and backside wafer-scale testing. The grating coupler has been designed for use in the AIM Photonics multi project wafer (MPW) platform, thus enabling non-contact optical interfacing irrespective of the wafer orientation. We have numerically demonstrated coupling efficiencies of 34% (-4.7dB) and 28% (-5.5 dB) for the wafer front and backside respectively while operating at a wavelength of 1550 nm. With proof of concept established, we foresee an eventual pathway for achieving higher efficiency isotropic grating couplers traversing into more 3D silicon photonic architectures.

We present a device using Shack-Hartmann wavefront sensor for measuring concave optical parts. A technique based on the device makes it easy to measure the main parameters of the aspherical equation of concave aspherical mirrors, radius of closest sphere Rv and eccentricity ε. The described method allows you to reconstruct the shape of the controlled surface in the form of an equation specified during its manufacture.

We developed Korsch type telescope for the compact advanced satellite payload. The optical system has a diameter of 600 mm with F/11. All mirror component was developed to have better performance than the tolerance allocations. The alignment of three mirrors are guided using the algorithm, merit function regression method. During this process we found a new approach for the far field focus optimization. To minimize aberration, we have been focused on the main Zernike term (astigmatism and coma), but the focal plane position is also important to proceed to the next step. We will present our optimization process, and the result of performance.

Large ground-based telescopes are prone to perturbations caused by environmental factors that affect the mechanical structure of the telescope that can cause collimation loss and image quality degradation. The Telescope Metrology System (TMS) is a metrology method under development at the Giant Magellan Telescope (GMT) and prototyped on the Large Binocular Telescope (LBT) to monitor and maintain collimation and pointing. TMS measures the precise position and orientation of a telescope’s primary mirror in relation to other telescope elements. Currently, prototyping has progressed to TMS operation at prime focus between LBT’s two 8.4m primary mirrors and the Large Binocular Camera (LBC), a pair of prime focus correctors and wide-field detectors. TMS utilizes a multi-channel absolute distance measuring (ADM) interferometer to create a laser truss by determining the distance between fixed points on the primary mirror and the LBC. By performing a kinematic analysis of the ADM data, the relative position and orientation of the primary mirror and LBC can be determined. With knowledge of the position of the telescope, an optical layout model can be created using TMS data as input. This allows for iterative simulation of field aberrations and loss in image quality due to misalignment of the telescope. This will allow for collimation and pointing to be actively monitored and maintained during an observation. This paper will discuss the process of implementing TMS on LBT and the challenges that arose.

Polishing precision optics is highly depending on the operator. Hence, a good result relies on a skilled optician who controls the process chain. This process chain consists of different manual steps such as loading, cleaning and calibrating different machines. To get more control over the process and to speed up the production we currently build an operator independent polishing cell using a single robot. Therefore, we positioned the robot in the middle of the production cell, which enables the robot to reach and manipulate different tools located around the kinematic. One major issues is the lower positioning accuracy and stiffness of an industrial robot in comparison to standard optic machines. Probably the most challenging step concerning accuracy in precision optics manufacturing is the interferometric measurement. In this paper, we present a method using an ESDI Intellium H2000 interferometer, designed for use in unsteady conditions. The robot positions the surface under test without the use of any additional mechanics to enhance the accuracy. The measurement position was manually teached in and approached several times for a statistically significant evaluation. The results show that the robot is sufficiently accurate and stable to perform interferometric measurements. This is a key element towards a completely operator-independent manufacturing cell for precision optics.

Optical interferometry is widely used for surface metrology, and phase-shifting interferometry (PSI) remains the “gold standard” for measuring surface form and texture. In the past, the environmental sensitivity of PSI relegated its use to dedicated metrology labs with well-controlled environments. As metrology requirements have expanded beyond the lab, advances in metrology techniques now enable high-precision optical testing in places previously considered inappropriate for interferometric techniques. A class of environmentally-robust methods preserve the gold-standard accuracy of PSI by measuring and accounting for rigid-body motions from vibration and large-scale airflow during the PSI acquisition. These methods, including model-based PSI, use a physical model of the interference to measure cavity rigid body motion and accommodate a wide variety of measurement geometries, surface shapes, surface departure, reflectivities, and environmental conditions without changing the user’s measurement process. For more extreme environments, spatial carrier methods analogous to off-axis holography extract the surface phase fast enough to “freeze” vibration and air turbulence in a single camera frame. The price paid for single-frame acquisition is a loss of lateral resolution as well as a modest increase in sensitivity to optical aberrations, requiring calibration for compensation. This paper will describe current techniques and methods, as well as provide examples and results for practical measurement scenarios in the manufacture of high-precision optical components and systems.

Deflectometry is a powerful measuring technique of complex optical surfaces. Usually a series of binary patterns or sinusoidal fringes are displayed on a screen, and correspondences are established between the screen and camera points according to their gray levels or phases. The image associated with a screen pixel is blurred due to the defocus and aberrations of the off-axis imaging system, and the calculated location of the correspondence point will in turn be biased. The space variant point spread function associated with the catadioptric system is analyzed based on the light field method, and the resulting blurring effect is then addressed using Wiener deconvolution algorithm. Henceforth the phase errors in the captured images can be compensated effectively. Experimental results are presented to demonstrate the feasibility and effectiveness of the proposed method.

We introduce the design of a highly compact, non-planar illumination source for deflectometry. The source emits uniform and Lambertian light from a curved area resembling the inner bore of a cylinder. When equipped with motion hardware, the ring source behaves like a spatially modulated screen with a pixel pitch comparable to that of a typical LCD monitor. If this source, a detector, and test optic are coaxially aligned, then on-axis deflectometry measurements are possible for axicons and centrally obscured, convex optics. This paper highlights the illumination design behind a cylindrical ring source and its implementation as a prototype in the visible spectrum.

Powerful and novel telescope design is key to pushing the available limits of astronomical sciences and a segmented primary is an attractive approach. For the Nautilus Space mission, a segmented lens has been proposed to replace large monolithic primary optics for the purpose of survey faint objects like exo-planets as well as time-domain astrophysics observations. Enabling technology for Nautilus is an ultra-lightweight multi-order diffractive engineered (MODE) lens that replaces bulky primary mirrors. The MODE lens consists of multiple, identical, molded segments. This is because the complicated optical design of both the diffractive surfaces is not easily manufacturable by traditional fabrication methods. Besides, the molding approach for identical segmented optics allows for a cost-efficient process. Conversely, the fusion of segmented optics demands high precision metrology and a delicate assembly strategy. We propose an in-process metrology technique that mitigates post-assembly process complications. This system monitors the co-phase character of the segmented optics during UV cured assembly, guiding the overall process.

The ability of space telescopes to see into nascent protostellar systems and even further into our universe is driven by the size of their deployable light collection area. While large monolithic mirrors typically weigh tons, inflatable membrane mirrors present a scalable, ultralightweight alternative. Leveraging decades of advances in adaptive optics technology, the possibility of a well-corrected 20 meter-class space observatory such as the Orbiting Astronomical Satellite for Investigating Stellar Systems (OASIS) is strikingly feasible. However, with great aperture size, comes great metrology requirements. Membrane reflectors are characteristically structured as one transparent and one metallized polymer membrane sealed around a steel tensioning ring. The inflated surface does not naturally conform to a known or prescribed conic but an approximate Hencky surface. Furthermore, multiple internal reflections and polarization interactions between the dielectric and metal layers disturb coherent light that probes it. A non-contact, full-aperture testing method is needed and further, one that can test highly varying membranes after thermoforming too. We present our method in obtaining the absolute shape of thermally formed, inflatable reflectors for space telescopes. Our work measures a 1-meter prototype of the OASIS primary inflatable mirror. Evolving from laser distance scanning to photogrammetry to deflectometry, our survey of metrology techniques for inflatable membrane optics is discussed.

Accurate system calibration remains an area of active improvement in deflectometry. Since deflectometry requires the geometry information of all participating hardware to be well known, miscalibration can mar the accuracy of surface reconstruction especially in lower order shapes. To uphold reconstruction fidelity, extra measuring instruments (i.e. coordinate measuring machines, laser trackers, metering rods) or reference features (i.e. fiducial points or reference mirror) to find out the positions of a camera, a screen, and a unit under test are used. These methods provide reliable calibration but are resource-intensive. In this paper, we introduce an alignment algorithm to calibrate the geometry of a deflectometry configuration. We leverage the concept of alignment algorithm which uses a sensitivity model. With the aid of ray tracing simulation, the relationship between camera pixels and screen pixels of a deflectometer is quantitatively established. This pixel-to-pixel relationship enables us to generate computational imaging of screen and characterize the tendency of misalignments of the deflectometer. On top of that, we can calculate and make multiplexed patterns of screen which highlight the effect of misalignments. We set specific indices and corresponding screen patterns for each alignment parameters to build the sensitivity model. The initial simulation result shows that the algorithm can estimate misalignment status. We believe that this algorithm can be an alternative and efficient calibration process for the deflectometry system, especially when the usage of extra measuring devices is limited.

The Predictive Thermal Control (PTC) project is a multiyear effort initiated in Fiscal Year 2017, to mature the Technology Readiness Level (TRL) of technologies required to enable ultra-thermally-stable ultraviolet/optical/infrared (UVOIR) space telescope primary-mirror assemblies for ultra-high-contrast observations of exoplanets. PTC has three objectives: validate thermal optical performance models, derive thermal system stability specifications, and demonstrate predictive thermal control. This paper reviews recent and previous accomplishments.

Methods of centering without using a precision rotary table to establish a reference axis in space are several times faster than with a rotary table. However, finding an optimum method of establishing an alternative reference axis is challenging. We look at the small class of centering situations involving the precision cementing of doublets to illustrate the advantages of using a Bessel beam as the reference axis. Two approaches to centering illustrate the method; one involving first aligning the meniscus element and then adding the positive element, and the other, cementing the two elements and aligning the pair.

With the continued development of multi-order diffractive engineered (MODE) lenses that consist of both multi-order diffractive surfaces and a diffractive Fresnel lens surface, it is becoming more realistic that these components may be used as an ultralight large aperture primary for space telescopes. As conceptual designs for these large primaries push the size limits of optics manufactured by compression molding, it becomes necessary to make a segmented MODE lens primary rather than a monolithic one. We use 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 modified ultra-fine alignment screws with ball bearings on the end that kinematically engage with the step-like features of the MODE lens surface (similar to a Fresnel lens) to constrain the segments in 5 degrees of freedom, leaving rotation about the optical axis unconstrained. The alignment of the segments is verified using multiple methods including a scanning white light interferometer and deflectometry. Such an alignment system has the capability of fixing the segments together in order to bond them with adhesive while aligned. These tests offer a proof of concept for a system that can be used for an eventual 0.24- m, compression molded, glass, segmented MODE lens.

Hyperion is a far-UV mission that investigates the birth clouds of stars using a 40 cm aperture telescope feeding an imaging long-slit spectrometer. The science requirements of the mission dictate that the spectrometer covers 140.5- 164.5 nm spectral range with resolution greater than 30,000. We employ smart and efficient design to create a longslit, cross dispersed, echelle spectrometer that utilizes a two-mirror freeform imaging optics. Echelle spectra for n = - 19, -18, and -17 over a 10 arcmin × 2.5 arcsec (length × width) FFOV are imaged onto the focal plane. We simulate the optical performance and the expected spectral efficiency.

The MicroCarb mission was initiated in Dec 2015 during the COP21 climate conference. Its objective is a better understanding of the carbon cycle within our atmosphere and thus enabling the prediction of its evolution. The French space agency CNES selected Airbus Defense & Space for the development of the satellite and its disruptive instrument with an original concept based on multi freeform mirror design. Safran Reosc was selected by Airbus for the optical manufacturing of all the key optical components of this innovative compact spectrometer, the first in EU of its class entirely based on precision freeform optics. We will first recall the benefits of using freeform optics in an imaging or spectral instrument. Then we will present the MicroCarb satellite and its instrument optical design. Joint design analysis was spent with Airbus towards ‘feasible’ optics despite the fact that this project constituted a unique opportunity for Safran Reosc to make a quantum leap in optical manufacturing and testing technology for precision freeform optics in Silicon Carbide (SiC).

Optical payloads are hosted on a range of spacecraft and reach orbit on a variety of launch vehicles. Traditionally, each payload imposes specific requirements on the mounts such as surface figure, thermal environment, and first dynamic mode. The product line of mounts described herein as the Common Optical Mount (COM) is designed to work for 80% of Lockheed Martin’s future space applications with no change to the design. Varying in diameter from 25mm to 300mm, each pre-qualified product line provides a different service needed while meeting general requirements and accommodating a wide range of unique optics (i.e. high precision alignment, large FOV systems, thick & heavy optics, lens, mirrors, beam splitters, diffraction gratings, etc.). Payload programs then leverage this qualified design and all the released piece part drawings. Additional requirements can be added to the base requirements for tailoring specific program needs. For example, the same mount product could be used to hold a fused silica beam splitter for a NASA mission in GEO orbit or a BK7 lens for a military customer in LEO orbit. Whether in a satellite constellation of a few large high-value exquisite systems or a prolificated LEO constellation of small satellites, the catalog of space qualified optical mounts serves to reduce cost, schedule, and risk for programs. COM helps deliver a payload that meets the customers future space architecture needs with improved capabilities at a fraction of the past costs.

Highly precise infrared lenses are used in a broad range of optical systems such as night visions, thermal imaging or gas sensing. As most infrared materials (e.g. Germanium, Chalcogenide glass) suffer from high Fresnel reflection losses, the use of anti-reflective coatings is state of the art to overcome this issue. An alternative approach is the implementation of anti-reflective microstructures into molded infrared lenses. This shortens the process chain and enables many advantages for example regarding the monolithic optic’s design. Precision Glass Molding (PGM), a replicative manufacturing technology, allows the macroscopic lens molding and the replication of surface microstructures to be carried out simultaneously. While PGM is an established process for manufacturing glass optics in general, there is a lack of knowledge regarding the replication of microstructures. This leads to the necessity to further investigate the PGM process chain for molding microstructures. The current paper addresses the process chain of manufacturing anti-reflective optics by precision glass molding. Process simulations are presented by a multiscale approach. In order to prevent wear, a suitable anti-adhesive coating system for molding tools with regard to the special requirements of microstructured surfaces is introduced. The results of the molding experiments highlight the importance of a multiscale simulation approach and demonstrate the stability of the anti-reflective microstructure.

Precision glass molding is a viable process for the cost-effective volume production of freeform optics. Process development is complex, requiring iterative trials of mold manufacture and metrology, molding prototyping, optic metrology, and functional testing. This paper describes usage of chalcogenide glass molding as a lower cost, faster turnaround mold prototyping process for an Alvarez lens intended for use in visible light. The target optic has a clear aperture of 42 mm, aspect ratio of 16:1, error specifications of 20 nm – 25 nm RMS across a spatial wavelength band from 1 mm to the clear aperture (e.g. form and mid-spatial frequencies) and microroughness of 2 nm Sq. The evaluation process uses diamond turning of trial molds in metal, molding of chalcogenide glass prototypes, and comparative metrology of molds and optics to close the manufacturing and metrology loops and more rapidly converge on a viable process starting point for visible glass.

We report a facile fabrication method of curved mirror with 3D printed plastic mold. Polylactic acid (PLA) is used as material for plastic mold. Polydimethylsiloxane (PDMS) replica is obtained from PLA mold, followed by planarization with spin-coating of additional PDMS. After ultraviolet (UV) treatment of smoothened PDMS replica, aluminum (Al) layer is deposited by thermal evaporation. Due to smoothened surface of PDMS replica, Al layer shows clear reflected image without perceptible lines, thereby functioning as a curved mirror. We expect that our curved mirror will be applicable to display and imaging devices.

Optical non-contact, interferometric measurement strategies for mold pins and plates provide an effective means for improving the consistency of the injection molding of small lenses for consumer devices. In this presentation, we describe high-precision interferometric metrology combined with motion systems and advanced software to address the wide range of length scales and metrology requirements of mold assemblies intended for high-volume production.

Transmissive optical components tend to be classified as either diffractive or refractive, based on which phenomenon more accurately describes the way they function. Although their optical functions are governed by distinct physical phenomena, Fresnel lenses are often confused or conflated with Diffractive Optical Elements (DOEs) like Fresnel zone plates and kinoforms; this is due to their similarities in shape, the method of defining their surfaces, and even the name. This research was conducted as an opportunity to describe the distinguishing characteristics of DOEs and Fresnel lenses, as well as the acceptable terminology to use with both classes of optics. First, background on diffraction and geometrical optics will be discussed, followed by methods used to design and fabricate both types of elements. Then, back focal distance metrology is performed to demonstrate the difference in function. The experiment performed supports the fact that DOEs and Fresnel lenses are not the same. This work is intended as a clarification of nomenclature and functionality, as well as an illumination of what makes DOEs and Fresnel lenses distinct.

Photonic devices based on polymer waveguides have potential use because they can be fabricated by high-volume manufacturing techniques. These integrated photonic devices can potentially be applied to communications and sensing as they can be produced in a short cycle and at low cost. In this report, we present foundry fabrication of polymer-based photonic integrated circuits. The inverted-rib waveguide components are about 2 μm wide and 0.570 μm deep. Spincoated SU-8 polymer onto SiO₂ is used to compose the guiding layer. In our preliminary results, we highlight the design, manufacturing, and characterization of microracetrack resonator notch filters. Those components were fabricated using complementary metal-oxide-semiconductor (CMOS) foundry process. Full wafers were processed at the foundry’s 150 mm-facility. Compact micro racetrack resonators based on SU-8 polymer are demonstrated, presenting high coupling efficiency. Facet sidewall roughness was reduced in the chip dies using mechanical polishing processes. We believe these results are promising for applications ranging from telecommunication components to sensing applications at low cost.

The requirement of the complex surface is increasing significantly with growing needs to fulfill the demands of many challenging applications. The advancements in manufacturing technologies attract optical designers to think about more and more complex shapes. The demand for hybrid surfaces i.e. diffractive structures over spherical, aspheric and freeform surfaces is growing for many future applications e.g. hyperspectral imaging, spectroscopy, beam shaping, wavefront coding. The hybrid freeform surfaces are the most complicated and most demanding surfaces for the above applications due to the advantages of the freeform base profile and diffractive structures. The use of these components leads to significant improvement in the performance of these optical systems along with considerable miniaturization and cost reduction. Challenges in fabrication and characterization of diffracto-freeforms are a limiting factor for its realization. This work aims to explore the fabrication and characterization strategy for diffracto-freeform optics. The cubic freeform shape with diffractive structures has been chosen for the study. The slow tool servo machining is utilized for the fabrication of this hybrid surface. The tool path development strategy and the effect of process parameters are discussed. The base shape and diffractive structures are characterized separately by utilizing the optical profiler measurements. The average error in the fabricated diffractive structures height and there radial distance from center is found less than 10% and 15% respectively. The characterization of the fabricated surface and fabrication issues are discussed in this paper. The current study is helpful to understand the various issues involved in the development of such complicated surfaces.

Increasingly, the optimal mirror material trade must reach well beyond textbook material attributes, and consider the richness and applicability of underlying statistically meaningful engineering data. The trade itself will have profound cost and complexity impact in the system implementation, from assembly, integration and test (AIT) through gravity and dynamic loading, and into operation under those influencing factors. Material selection is a multi-parameter decision, having significant performance and cost implications on higher level system attributes. We note that for most situations, an astronomical optical telescope will not be isothermal, and strategies based on this assumption are limited where ultimate performance is expected. Attributes like inhomogeneity or anisotropy of thermal characteristics can dominate. We summarize material attributes that should be considered in material selection, and reference these attributes to those of ZERODUR.

G-release – defined as the knowledge uncertainty of a mirror’s gravity-sag or the residual error between the mirror’s predicted and actual on-orbit shape – is a critical error budget element for space telescopes. For a UV/Optical telescope, G-release needs to be less than 4 nm rms. Absolute metrology techniques developed for high-accuracy optical surface testing can be used for characterizing gravity-sag of space optics. This paper presents the importance of gravity sag for space optics and reviews methods for its compensation, characterization or correction.

We describe a coronagraph-like instrument for the characterization of fabrication errors in diffraction gratings and diffractive optics. A diffraction grating under test is illuminated with collimated laser light, and a reflected diffraction order is focused by a lens. A beam stop placed at the focal plane of the lens blocks the primary diffracted beam, passing only the small fraction of light scattered into nearby angles due to fabrication errors. The transmitted light fraction is focused by a second lens onto a digital camera and the light distribution is measured with a sensitive high dynamic range imaging method. Preliminary measurements with the coronagraph setup are compared to focal-plane images made without beam stop.

The use of electronic imaging systems in the automotive industry has increased dramatically as a result of the wide spread implementation of optical-based safety systems and driver assistance features in new vehicles. The challenging environmental requirements for automotive cameras have given rise to the need for image quality testing of these cameras over a wide range of operating temperatures. Functional and survivability testing of camera assemblies is relatively straightforward and may be carried out in conventional environmental chambers, but assessing the imaging performance of the lens over temperature is critical in evaluating whether hardware performance meets design intent and presents a much more challenging metrology problem. The lens must be contained within a chamber, but the chamber itself must not adversely contribute to the image quality being assessed. Measures must also be taken to prevent condensation in the optical path when operating below the ambient dew point. Additionally, careful consideration must go into the measurement of defocus over temperature – which is the critical metric in temperature testing – to ensure that the chamber is not contributing to the measured focus shift. In this paper, we describe an innovative system that takes these challenges into account and enables users to measure lens image quality metrics over a temperature range of -25°C to 105°C. This system has evolved over the past few years from a strictly in-house laboratory setup to a recently released commercial product, and we will present results from our extensive testing that show good correlation of measurements to modeled behavior.

The CaF2 optical lens was widely used from ultraviolet- to infrared- wavelength range. The CaF2 has optical properties with high transmittance and low reflectance. Usually, it used for laser optics, excimer laser, CaF2 Lens, ultraviolet to infrared lens and cryogenic cooling thermal imaging systems. It is usually difficult to machining using natural diamond tools, because CaF2 is a brittle material. In theoretical calculations and experimental verification, we executed the ultra-precision machining of CaF2 lens by using the Single-point diamond turning machine(DTM) with laser-assisted modules. The machining of CaF2 materials is affect the negative angle of a diamond tool and laser power, etc. Repeated experiments show that surface of the CaF2 lens more than 150% better by using laser-assisted modules and negative angle tools than conventional DTM machining.

A number of process steps that build on one another are required to manufacture optical components from glass. The polishing steps are the most time-consuming and therefore cost-intensive parts of the process chain. Low removal rates and the depth of the Sub Surface Damage (SSD) to be removed contribute to this. An alternative for the complete removal of the SSD-penetrated material using contactless polishing methods such as Ion Beam Figuring (IBF) is the healing of the SSD. Due to the induced energy during laser-polishing, the material is remelted at the defects and the SSD are closed. However, laser-polishing is also associated with disadvantages in terms of shape accuracy and surface quality. The project HyoptO is therefore devoted to the development of a hybrid-process-chain consisting of laser processing and conventional polishing. It is expected that the healing times of the SSD can significantly reduce the process times in the subsequent polishing steps. However, there are a few questions to be answered regarding the economic use of the hybrid-process-chain. These include:

The Development of technology is causing the smaller devices. So, optical components are decreasing in volume. For example, the DOE(Diffractive Optical Elements) Si lens is thin than a lens, it was usually used for biomedical devices, hologram, optical sensor, mobile phone, etc. But the fabrication of the DOE Si lens have very limited to machining. The ultra-precision machining of DOE by using the DTM(Diamond Turning Machine) could have cause surface defects such as whitening phenomenon and rainbow effect on the surface. This problems cause optical defect such as a scattering of light. We carried out a ultra-precision machining of the DOE(Diffractive Optical Elements) Si lens by using the DTM with laser assisted module. We can be optimize the machining conditions in several machine processes, such as edge angle of diamond tool, power of laser, cutting depth, feed rate. As a result, we are successfully machined the DOE Si lens with a surface roughness of several nano-meter

Variations of the induced retardance in the aperture of liquid-crystal variable retarders LCVR and spatial light modulators LC-SLM are measured. It is found that the induced retardance, in LCVR, shows variations over the aperture which depend on the wavelength of the light used and the voltage applied. Larger retardance variations appear near to the edges of the cell. There are also larger variations in the maximum and minimum unwrapped retardances in the retardance versus voltage curves. These voltage values and the edges positions of the cells should be avoided in applications of these devices. On the other hand, the induced retardance is calculated pixel by pixel in LC-SLM. For the same gray level over the entire LC-SLM screen, there are differences in the induced retardance between pixels located in a central area and pixels located in the edges. For correct calibration of the LC-SLM, the retardance value as a function of gray level was determined, pixel by pixel.