This PDF file contains the front matter associated with SPIE Proceedings Volume 13728, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

The supply chain for infrared optical materials has been significantly impacted by recent geo-political events ranging from export restrictions and tariffs to global conflict. A review of the feedstocks and supply chains of the primary common infrared optical materials including germanium, zinc sulfide, zinc selenide, silicon and the chalcogenide glasses is provided. Recent geo-political considerations are reviewed and speculation on strategies for future supply chain assurance are discussed.

The AmeriCOM facility located in Fairport NY, is a not-for-profit research service center that offers manufacturing and testing services to support the domestic optics industry. Recently, there has been growing interest in re-shoring domestic manufacturing. Precision optical components are receiving particular attention due to their critical role in national defense and security. American manufacturing must be more strategic to compete with overseas markets. By investing in advancements in automation and machinery, it will increase manufacturing throughput. This enables working smarter, not harder to offset labor cost disparities. The final stage of the optical manufacturing process includes polishing. This process still demands considerable manual labor, especially for high-volume components such as spherical refractive optics. Sub-aperture polishing machines were introduced to bring a determinism to the process. Using advanced software algorithms and precise machine motions, these new polishing machines can control material removal rates, target specific form and figure specifications and improve surface roughness. The sub-aperture process utilizes small contact area tools that strategically target material removal based on a material removal factor (also known as the tool influence function). The software requires proper data input and orientation. The algorithm calculates the toolpath based on the material removal factor and the error to be corrected. Material removal rates are slow and can create mid-spatial frequency patterns in the surface that can be difficult to remove and cause image quality issues. A new approach to deterministic polishing is presented utilizing a near full aperture tool that would remove bulk material, remove subsurface damage from the surface of the substrate, and reach the targeted radius of curvature and figure error. A deterministic process is one in which no randomness is involved in the development of future states of the system. This means that given a specific initial condition, the process will always produce the same output with 100% certainty. In other words, a deterministic process allows for precise predictions of outcomes based on known inputs. In this study AmeriCOM has collaborated with Lawrence Livermore National Laboratory, OptiPro, and LaCroix Precision Optics to develop high-speed CNC, near full-aperture deterministic polishing process for both individual monolithic surfaces and multi-block tools. This study provides updates on efforts to achieve fully deterministic control across the aperture using compliant polishing tools and improved environmental controls.

The manufacturing of precision optical components demands an exceptional degree of control, consistency, and understanding of complex physical processes. From grinding and polishing to metrology and defect correction, every stage relies on nuanced decision-making informed by years of operator experience and process feedback. As demands on optics continue to increase—in laser damage resistance, surface form accuracy, and throughput—traditional methods alone are increasingly insufficient in the 21st Century workforce. This talk explores the integration of artificial intelligence (AI) into precision optics manufacturing workflows, emphasizing how data-driven models and machine learning can enhance process definition and help enable machine maintenance. We will examine examples where AI augments fabrication tasks such as grinding, polishing and centering as well as the implementation of predictive maintenance models. Attendees will gain insight into the challenges, opportunities, and potential best practices at the intersection of AI and optical fabrication, setting the stage for improved processing times and greater product throughput.

Advanced optics components are continuously gaining importance in numerous high-tech applications. Their shape can range from rather simple aspheres to complex freeform surfaces with part sizes ranging from micro lenses, e.g. for endoscopes, to meter-sized optics for lithography or space applications. The manufacture of these optics usually comprises of a process chain that includes several rough, fine and ultra-precision grinding steps to generate the general shape as well as various polishing steps to obtain an optical surface finish and to correct shape and mid-spacial frequency errors. In this context, OptoTech provides a complete portfolio for the production of precision optics from proper tooling and fixtures, over advanced grinding and polishing machines to dedicated metrology equipment. In addition, the competence of the processing experts is offered for customer-oriented development of new processes and process chains as well as for the optimization of existing processes. This presentation will introduce some recent developments of OptoTech in the field of ultra-precision grinding, polishing and digitalization.

Phase-shifting interferometry is the gold standard for precision surface and wavefront metrology, but it is fundamentally a comparative measurement. The resultant phase map is a measurement of the optical path difference (OPD) between the test and reference wavefront of the instrument across the field of view. The measured OPD includes any surface form irregularities from the reference surface, directly contributing to measurement error. For valid estimation of OPD, the total error contribution must be adequately small when compared to intended test wavefront. Existing methods to mitigate this error include polishing the reference surface to a high degree of accuracy or performing in-situ calibrations, which can be costly, time-consuming, error-prone, and require a high level of operator expertise. This paper discusses an automated method to mitigate reference surface error that improves upon current methods. The surface error may be characterized by the manufacturer using high-precision absolute calibration methods and loaded onto on-board storage. Electronic communication between the instrument and the calibrated accessory allows automatic figure error correction by retrieving the figure error data and deriving a scaled and laterally registered correction at point-of-use, with no operator intervention. Considerations to successfully employ this method are discussed in the context of transmission spheres and flats. Measurement results with residual form error on the level of a hundredth of a wave are demonstrated, despite the use of reference elements with intrinsic figure errors no better than a twentieth of a wave.

With ongoing labor shortages and a shrinking pool of experienced technicians, automation is becoming increasingly essential in the field of optics fabrication. By integrating robotics into the manufacturing process, companies can significantly increase production capacity and operational efficiency while relying on fewer human resources. Repetitive and labor-intensive tasks that often lead to worker fatigue and burnout can now be managed by robots, freeing skilled technicians to focus on higher-level tasks such as process optimization, quality assurance, and system maintenance. One of the key benefits of automation is the ability to reduce downtime between parts and enable continuous, lights-out manufacturing. This leads to higher machine utilization rates, increased part output, and improved profitability. Automation also enhances consistency and repeatability, which are critical in optics fabrication where tight tolerances and high precision are required. This presentation highlights several of OptiPro’s advanced automation solutions. OptiPro has developed a range of off-the-shelf and customized automation solutions specifically designed for optics manufacturing. These systems focus on part handling, robotic integration, and metrology. The Revel, a robotic beveling system designed to perform consistent, unattended beveling of parts. Also featured are some of OptiPro’s automated part loading systems, which increase machine utilization by streamlining the handling of optical components. Together, these technologies demonstrate how integrated automation can improve throughput, consistency, and overall manufacturing performance.

The rapid expansion of the “new space” industry is leading to an unprecedented demand for high-precision mirrors. A combination of aluminum mirrors and diamond machining shows the potential to be a successful strategy for meeting these demands. This presentation includes an analysis of the limitations and challenges in manufacturing metal optics from aluminum. It shows the influences on the roughness and the achievable form accuracy and draws a comparison with alternative manufacturing techniques.

In astronomy, compound freeform surfaces, including multiple sub-components and sub-apertures, are frequently seen in integral field spectrographs (IFSs). The GIRMOS image slicer unit has 42 toric surfaces, each measuring 270μm in width and 6mm in length, with tilts in both the x and y axes. Achieving the required surface roughness is a crucial factor in assessing the performance of high-precision optical mirror surfaces. This work presents a model for simulating surface topography in ultra-precision diamond machining (UPDM) of toric surfaces resembling image slicers. The surface profile on a single feed constitutes the fundamental unit of surface topography. The existing model incorporates the kinematics of the diamond turning process, defined by machining parameters and the corresponding vibrations between the tool and the workpiece in both the x and y directions. The influences associated with the duplication effect models of the tool edge profile, comprising the nose radius effect, waviness effect, material spring back, plastic side flow, and material defects within the 2D profile, are analyzed. The comparison uses a full-nose radius profile and a half-nose radius profile for a better understanding of tool selection as per the image slicer geometry, including variation with respect to vibrations, feed, tool nose radius, and tool edge waviness.

The demand for freeform optical components is rapidly increasing in emerging technologies such as augmented reality, advanced imaging systems, and compact spectrometers. Fast Tool Servo (FTS) diamond turning has proven to be a promising technique for high-speed, high-precision machining of these complex surfaces. However, achieving nanometric form accuracy remains a considerable challenge due to dynamic servo-induced errors, particularly overshoot and control delays. In this paper, we present a novel technique used for analysis and compensation of surface form error for optical surfaces machined with an FTS. The difference between commanded axis position and actual axis position, commonly referred to as Following Error (FE), is typically dominated by the delay in time between commanded and actual axis motion. By shifting the actual FTS position by this known time delay and subtracting it from the command position, we remove the dominant component of the FTS FE and introduce the quantity known as Time Shifted Following Error (TSFE). By running an FTS in the air and analyzing TSFE before cutting, it becomes easy to characterize and compensate for subtleties in the commanded FTS position that would otherwise impart figure error onto a machined surface. In this way, it is possible to optimize FTS cutting conditions based on various parameters including FE amplitude, position overshoot, and settling time between features. Experimental validation using a dual-sinewave freeform surface demonstrated a peakto- valley (PV) form error reduction of 56% compared to machining without compensation. Additionally, data for a radial saw tooth type surface is presented and analyzed.

The latest developments in the market create a need for large-scale mirrors and off-axis paraboloids. To cover these needs the diamond turning machines IL1200 and IL1600 have been developed and will be introduced from machine design to available modules. It will give insides to machines that can produce parts to a diameter of up to 1.6 meters.

We present a path toward scalable manufacturing of freeform optics using effective reference structures (RS). Through a literature and industry survey, we identify qualitative requirements for effective RS and introduce an automated CAD tool that generates NURBS-based optical models with user-specified RS. We validate this tool through the fabrication and metrology of a toroidal mirror and propose a modular experimental framework using an anamorphic asphere to quantitatively assess RS effectiveness. Our work enables registration and alignment with quantifiable precision across the optical manufacturing process chain, laying the foundation for automated, application-specific freeform manufacturing workflows.

Laser-assisted diamond turning (LADT) has emerged as a promising technique for machining brittle materials, enabling the precision fabrication of optical components previously unsuitable for single-point diamond turning (SPDT). In this work, we evaluate the effectiveness of LADT on glass (Fused Silica) substrates by comparing the resulting optical surfaces to those produced by conventional generation, with a focus on the required post-processing effort to remove subsurface damage (SSD). Following initial shaping either by LADT or conventional generation each surface was subjected to magnetorheological finishing (MRF) in 1-micron increment uniform removal. Surface roughness and the presence of defects such as pull-outs were monitored after each increment. The point at which surface roughness plateaued and no further defects were observed was taken as the threshold for sufficient SSD removal. Results show that LADT-treated surfaces require significantly less material removal to reach this threshold, demonstrating the technique’s potential to enable direct fabrication of complex optical geometries with significantly reduced SSD and corresponding bulk removal.

As the demand for lower surface roughness precision optics increases for high tech applications, polishing solutions that can achieve low surface roughness are needed. Pureon is committed to developing advanced polishing solutions for the precision optics market. To that end, we have turned our attention to optimal processing of Calcium Fluoride (CaF₂). CaF₂ has a broad wavelength transparency that allows it to be used in both ultraviolet (UV) and infrared (IR) applications. This is especially important for applications that require both UV and IR transmission like spectroscopy and imaging systems.¹ Precise polishing is needed to achieve a certain surface quality that is necessary for the final application. CaF₂ has a low hardness (Mohs hardness: 4) and is a brittle material; properties that can lead to increased edge chipping and insufficient surface quality.² Precision optics are commonly polished with cerium oxide abrasive slurries due to its inherent ability to exhibit both chemical and mechanical activity.³ The efficacy of cerium oxide abrasive slurries in CaF₂ processing is limited due to residual cerium oxide that is surface bonded. This residue proves difficult to clean and results in increased absorption in the UV wavelengths.⁴ To achieve a high surface quality with efficient processing times, Pureon has developed the ULTRA-SOL^® AlumaGem platform that utilizes both precisely graded diamond and alumina abrasives dispersed and suspended in an optimized carrier fluid for the bulk and final polishing steps. AlumaGem is a flexible platform that can be built with a range of diamond types and sizes depending on an application’s need. An in-depth study will be presented using 3 μm and 0.25 μm AlumaGem to process CaF₂ from ground to final polish with various polishing pads.

An optic is a lens or other component in an optical device. Light passes through or reflects off an optic. To achieve a quality optical surface, the surface of the optic must be polished. This study explores the effectiveness of three different polishing fluids used to polish BK7 optical glass. BK7 is a popular material used to make precision optics due to its clarity and low dispersion, making it ideal for precision components like lenses and prisms. Polishing is a necessary step in achieving the desired surface quality for optical performance. This research project conducted a series of controlled polishing tests utilizing the modern manufacturing equipment and metrology methods to evaluate the performance properties of each polishing fluid. Using metrics that are standard manufacturing specifications, data was collected evaluating the surface roughness using white light interferometry microscopy, surface figure using phase shifting interferometry, and material removal rate measured by thickness change. The goal was to determine if there were significant performance differences between slurries. The findings provide important insights for optical manufacturers looking to optimize their polishing processes for high-precision optical glass components. Comparing the different fluids, this study provides information used by precision optics technicians when selecting polishing fluids for optical polishing applications.

WAPOP developed by the authors achieved atomic-level smoothing of silicon, reaching an RMS roughness of just 0.5 Å using only a PMMA plate in water. Its simple, slurry-free approach makes it highly promising for delivering the ultra-high precision needed in X-ray mirror fabrication.

We demonstrate high-precision femtosecond laser polishing and figuring of fused silica, achieving sub-nanometer surface roughness with nanometer-scale material removal precision. To the best of our knowledge, this is the first demonstration of fused silica polishing and figuring using femtosecond lasers while maintaining sub-nanometer surface roughness without introducing mid-spatial-frequency errors or subsurface damage to the initial surface. We identified the number of passes as a key parameter for controlling material removal rates during laser processing, enabling scalable material removal for large-area processing and the fabrication of diverse geometric features. Importantly, surface transparency is maintained with 99.5% transmission preserved throughout the process.

Rapid advancements in optical technologies are driving components to new extremes in performance requirements, challenging the ability of traditional metrology equipment to keep up. This has created a growing need for customized measurement systems that can deliver the precision and dynamic range required for demanding applications. As a manufacturer of optical components, Edmund Optics regularly uses spectrophotometers to measure the transmission and optical density (OD) of optical filters. Due to the limitations of commercial spectrophotometers, we have collaborated with Teledyne Princeton Instruments (TPI) and Spectroscopy & Imaging GmbH (S&I) to build a custom spectrophotometer to meet our internal metrology and our customer’s needs. We have developed a Custom DualVista Spectrophotometer: a dual monochromator system with a high brightness light source. TPI produced the dual monochromator with grating turrets, allowing for gratings to be repeatably switched with up to three distinct measurement regions. S&I produced the sample chamber and wrote the spectrophotometer control software allowing for automated scanning and report generation. Automation is critically important as this spectrophotometer is used for the characterization of our optical filters in production, not just as a system for research and development. So far, the development has been focused on ultraviolet and visible spectral measurements, achieving values greater than OD 8 for the majority of this spectral region. These capabilities can be shown measuring Edmund Optics’ bandpass, shortpass, longpass, or notch optical filters. We will show the custom spectrophotometer’s performance advantages over other commercial spectrophotometers commonly used by filter manufacturers, covering measurements of bandpass and notch filters, as well as edge steepness comparisons.

High energy lasers have applications in manufacturing, material processing, defense and research. As laser powers have scaled to the hundreds of kilowatts, the optics and optical coatings used in the laser must be manufactured to minimize absorption, scatter, defects, and foreign object debris (FOD) which can lead to loss in output power or at worst catastrophic failure. Extremely accurate metrology methods are required to characterize the low optical losses of high energy laser optics and a lack of standardized measurement protocols lead to concern about the reproducibility and repeatability of these measurements across industry. Two commonly used metrology methods for very low optical loss measurements are cavity ringdown spectroscopy (CRDS) and photothermal common path interferometry (PCI). A round robin format gage repeatability and reproducibility study was performed to characterize industry wide uncertainties in these measurements at several optics manufacturers and research institutions. Results show the largest source of measurement variance was reproducibility across study participants indicating the need for better calibration standards and consistent measurement protocols and training across industry. A high energy laser thermal scanning method is presented as an alternative to detecting sparse defects on high energy laser optical surfaces.

As the demand for high precision optical components increases, so does the demand for a full metrology suite to precisely characterize demanding specifications. We present on a phase metrology method that integrates an automated commercially available motion control system (i.e. external polarizers) with the (built-in) automation of a commercial RT spectrophotometer. We demonstrate the technique to produce low-noise verifiably accurate phase-measurements for phase-correction coatings for room prisms such as Pechan/Schmidt prisms used in certain high-end binoculars as well as some recent results on ultra-fast phase-shift mirrors currently in development.

Optical coatings standards have been written to enable users to rigorously specify optics for optical production. These ISO 9211 standards are now in an excellent position for even wider adoption and use. Improvements are now being implemented to assist users of the international optical drawing standard series, ISO 10110, to allow easier and more powerful ISO 9211 notation for optical coatings on drawings. In this paper, we explain some of the most recent changes to the ISO 9211 optical coating standards and how these changes can be used to make superior optical drawings for production.

Automation in optical component manufacturing reduces costs and boosts efficiency, driving adoption in precision optics. Automated surface quality inspection offers objective, traceable surface analysis, improving process control and reducing inspection errors. While dark field imaging excels at detecting light-scattering defects like scratches and digs, it misses reflectivity-based issues such as coating defects. Bright field imaging addresses this by detecting changes in reflectivity or transmission. Combining both techniques with image processing and machine learning will enable comprehensive defect inspection and classification.

We report on Multi-Spectral Low Coherence Interferometry (MS-LCI) as an optical, non-contact, thickness measurement and material identification system for glass and polymers used in laminate applications such as safety glass and transparent armor. Developed as a method to measure group refractive index (GRI) of materials, such as hydrated contact lenses,1 MS-LCI can distinguish between different types of glasses and polymers. In this work, the authors measured and report on several different materials. BK-7 was used as control sample for testing the material fit and identification algorithm used for this work. The authors speculate that MS-LCI will prove useful for material confirmation and non-destructive testing of transparent materials.

Transmitted wavefront error (TWE) measures how much an optical system’s output wavefront deviates from the wavefront prescribed by the optical designer. TWE captures system-level errors, such as assembly misalignment and mounting stresses, and directly characterizes the as-built performance of the system. Laser Fizeau interferometry is the workhorse for TWE measurement, but specialized null correctors are required to measure aberrated wavefronts that have a large departure from the ideal spherical wavefront. Computer-generated holograms remain the gold standard for testing a single component at volume; however, they are costly to design and fabricate and can be challenging to align in test setups. To address this inflexibility, scanning Fizeau interferometry—an established solution for aspheric surface metrology that does not require null correctors—was extended to measure TWE in aspheric wavefronts. The technique involves axially scanning the part under test and a reference surface within a spherical Fizeau cavity and reconstructing the TWE from annular zones of low fringe density. This was implemented on a commercial Zygo metrology platform for Fizeau interferometry and direct TWE measurements of five off-the-shelf plano-convex lenses were performed. To validate these measurements, ray-tracing simulations of the Fizeau cavity were created in Zemax OpticStudio, where independently measured as-built lens errors for each lens were supplied as inputs. The average peak-to-valley difference between the direct TWE measurements and the simulated TWE measurements was found to be less than 20 nm. This close agreement demonstrates potential for flexible and part-agnostic metrology of aspheric transmitted wavefronts—offering a practical alternative to complex and costly setups that require null correctors.

Aspheric surfaces provide significant benefits to optical systems. In asphere fabrication, metrology is key to enabling efficient production. Several precision metrology capabilities exist, including interferometric null testing and interferometric subaperture stitching, each with distinct benefits. Interferometric null tests require a custom nulling optic, and the computer-generated hologram (CGH) is commercially available to fulfill this need. But there are important considerations for alignment, calibration, and analysis required to achieve maximum benefit. The Aspheric Stitching Interferometer (ASI™), a multi-axis automated interferometric workstation, is a highly capable and proven asphere metrology system, but acquisition time can limit throughput, and measurable surface asphericity is limited by slope departure from best-fit sphere. We aim to simplify the user experience in aligning, acquiring, and calibrating CGH null measurements, and improve the throughput and aspheric departure that can be achieved by the ASI. We achieve this by integrating a CGH module into an ASI, combining the accuracy and alignment features of an Arizona Optical Metrology (AOM) CGH with the automated multi-axis workstation and software of the ASI. We detail the basic tasks in making a CGH null measurement using the ASI, including the alignment of the test asphere, vertex radius calculation, and error compensation. We demonstrate software-assisted alignment techniques for the CGH and test surface, as well as automatic compensation of systematic errors. Integrating the CGH null element and ASI motion system and software leverages the strengths of each technology and streamlines the measurement process – ideal for production environments with operators and technicians. It also provides a path to subaperture stitching with a CGH, enabling interferometric measurement of larger aperture convex aspheres.

The Optical Systems Technology (OST) program at Monroe Community College (MCC) in Rochester, NY trains optics technicians for careers in photonics manufacturing – a sector that strongly needs their skills. Vibrant industry support plays a critical role motivating students to pursue this rewarding career path by exposing them to diverse employment opportunities and helping them see the return on their educational investment. In this paper, we summarize MCC’s current practices for directly involving industrial partners in the education process, including program advisory board participation, adjunct instruction, company presentations and facility visits, internship promotion, apprenticeship support, resume and cover letter review, and job interview coaching. We also discuss potential builds on these practices such as formal internship tracking and professional mentoring. These practices illustrate how strong educational–industrial collaboration supports both student success and the growth of the photonics workforce.

As optics and photonics-enabled technologies become increasingly essential to modern life, the demand for skilled optics technicians is surging across the U.S. However, a critical shortage of trained workers threatens progress in this critical field. To address the gap, the American Center for Optics Manufacturing (AmeriCOM) is leading a national initiative to expand and strengthen precision optics workforce training. Monroe Community College (MCC) in Rochester, NY, launched the first Optical Systems Technology associate degree program in the nation. Through strong partnerships with industry, government, and the community, MCC has become a national model, achieving 100% job placement for its graduates. Yet, the growing demand outpaces the capacity of any single institution. Recognizing this, the U.S. Department of Defense charged AmeriCOM with scaling MCC’s success nationwide. This presentation explores how MCC and AmeriCOM are building innovative training pathways to strengthen the U.S. optics workforce and meet the industry's growing needs.

This paper describes three relatively new classes of optical plastics offered by the Fiber Optic Center. The three classes comprise a line of high RI polyesters (OKP), a new type of polycarbonate (TARFLON^TM) with improved properties, and new high temperature tolerant polyarylates (U100/T200). The optical, thermal, and mechanical properties are presented here as are a number of comparisons with known resins where improvements are highlighted. Finally some present and potential applications are discussed.

Single-point diamond turning (SPDT) of aspheric lenses is desirable for low-volume, high precision manufacturing. However, diamond turning of optical glasses for use at visible wavelengths presents significant challenges. A glass/polymer hybrid doublet aspheric lens was fabricated by applying a thin layer of optical polymer to a glass PCX lens substrate and diamond turning an aspheric profile into the polymer surface. A transmitted wavefront error of 1/4 wave PV at 633nm was achieved from a 15mm diameter, 0.3NA aspheric lens made by this glass/polymer SPDT method, with cyclic olefin polymer Zeonex K22R cemented onto an off-the-shelf f/1.5 22.5mm N-SF5 PCX lens. Comparison is made to similar all-glass, polished aspheric lenses, demonstrating comparable transmitted wavefront accuracy.

The Size, Weight, and Power (SWaP) challenge drives the development of compact, lightweight, and energy-efficient optical systems, particularly for infrared imaging and multispectral optronics. Femtosecond-Laser- Direct-Writing (FLDW) enables permanent, three-dimensional modification of the refractive index inside transparent materials. This opens new degrees of freedom for implementing gradient-index (GRIN) and freeform optics in bulk substrates. In this work, we investigate the femtosecond laser inscription of optical functions in Corning 9754 commercial glass, transparent from visible to mid-IR. We characterize the processing windows that yields homogeneous, low-scattering refractive index modifications, and we develop a quantitative link between laser parameters and induced optical phase. These results enable the design and fabrication of GRIN microlenses and phase components, evaluated through both wavefront measurements and imaging performances. The proposed workflow demonstrates the potential of femtosecond laser inscription for the realization of optical functions, paving the way for compact architectures dedicated to SWaP-limited applications.

We present an investigation on femtosecond laser as an alternate non-contact figuring and finishing method to address the need for high-precision and highly flexible sub-aperture optics fabrication. To demonstrate this method we fabricate a uniform array of microprisms on the surface of Borofloat 33 glass. This microprism array is predicted and fabricated demonstrating deterministic material figuring while maintaining the sub-nanometer surface roughness. Combining the figuring and finishing as a single step solution in a laser-scanning-based system provides a foundation for efficient and highly scalable ultrafast-laser-based fabrication of freeform optics.

For lenses, the alignment between front-, back-, and outside cylinder is just as important as the surface form errors. This is especially challenging for lenses containing an aspherical or even freeform surface. The NMF non-contact measurement machine range by QED Technologies allows flexible and high point-density measurement of freeform optical surfaces. It has a cylindrical coordinate measuring machine setup with an optical probe. A high-stability separate metrology system relates the probe position to the product position. This gives the versatility to measure all sorts of dimensions and surface shapes (flat, convex, concave, asphere to freeform with up to +/-2.5 mm departure from the best-fit asphere), the accuracy to measure with nanometer level accuracy, and the speed to gather the required high data density to characterize midspatial content. The machine has recently been equipped with an additional tactile probe for measurement of reference fiducials. A modification of this probe now allows to simultaneously characterize the front surface form error and backside alignment, centration, and lateral displacement; all without the need for dedicated tooling or product holders. With this tactile probe the centering parameters can be measured in the same coordinate system as the optical surface, allowing for either fitting the front surface relative to the backside surface or vice versa in 6 degrees of freedom. This method has been applied to an aspheric-plano lens, measuring the centering tolerances to single micrometer accuracy. For verification of the accuracy and repeatability, the same method has been applied to a reference sphere.

Nanotech’s Process Development Center has undertaken to develop tool-normal tungsten carbide mold grinding on the 250 UPL-MPG platform. This innovative machine possesses capabilities to enable the fabrication of intricate optical surfaces that are not practically possible with traditional cross-axis grinding platforms. Along the way, Nanotech has also worked with grinding tool suppliers to develop unique tool designs that have demonstrated world class precision and durability. The technique developed is evaluated and demonstrated by metrological results of gullwing aspheric lenses that have very high curvature and slope reversals. The reported results were obtained using the Panasonic UA3P-400T to measure lens form with the top probe along with pin size and feature concentricity with the side probe. The NewView 9000 was used for roughness measurements.

Lapping is an important dimensioning and finishing technology that is used in many different industries including metal, electronic, and optical component fabrication, as well as silicon wafer production. In each of these applications lapping is used to produce substrates of a controlled thickness, shape, and surface roughness. 3M^TM Trizact^TM Diamond Tile has been successfully used to lap a variety of glass types (Schott N-BK7^®), Fused Silica (Corning^® 7980), crystals, and IR materials on double sided machines for many years. Only more recently was a flexible version of this pad readily available, which allows for use in the lapping, or smoothing, of spherical lenses.

When combined with soft nanoimprinting, grayscale lithography (GS) offers a powerful and low-cost alternative to traditional etch-based methods for high-quality diffractive optics. Unlike etching, which faces challenges in surface roughness, aspect ratio control, and multilevel patterning, GS enables continuous relief profiles in a single exposure step, transferred with high fidelity through nanoimprinting. We demonstrate this approach by fabricating various diffractive optical elements (DOEs) for three applications. First, a 10π harmonic Fresnel lens shows advanced chromatic aberration correction compared to the traditional 2π Fresnel lens. Second, a high-quality computer-generated holography produces fine spatial features. Third, a reflective DOE exhibits a designed bidirectional reflectance distribution function. These results confirm that the combined GS and nanoimprint process not only overcomes key drawbacks of etching but also expands the design space for advanced diffractive optics in imaging, augmented reality, and compact optical systems.

This presentation highlights recent advances in 3D printing of glass micro-optics, focusing on new material systems, high-resolution fabrication techniques, and integration strategies. We showcase innovations that enable tunable transparency, multi-refractive index components, and complex optical geometries with sub-micrometer precision. Practical applications and emerging opportunities in imaging, sensing, and photonics will be discussed, along with key challenges that must be addressed to bring these technologies into mainstream optical manufacturing.

Non-contact in-situ point sensing can be a powerful tool for optics fabrication. Chromatic confocal sensors are adaptable, robust and can be used as feedback in a range of fabrication scenarios. Specific cases that illustrate this utility are discussed for diamond turning, though application to grinding, corrective polishing and additive manufacturing can be inferred as well. Techniques and methods for alignment and data acquisition as well as other considerations are illustrated. Examples include form error metrology of aspheric and freeform surfaces, relational metrology, closed-loop error compensation and part alignment. Limitations and special considerations are also discussed. For form error metrology, specifically, alignment of the sensor to the machine axes is critical and can have a significant impact on results. Particularly, the involvement of rotary axes presents specific alignment challenges. Additionally, inherent sensor errors such as the angle of incidence (AOI) errors present in all chromatic confocal sensors require specific assessment and compensation techniques, including artifact-based alignment and measurement. Data acquisition methods are also important for achieving desired results and performance. Data rates and synchronization between axis encoders and probe signals is essential when continuous data acquisition, such as spiral or raster scanning, is used. This illustration of practical cases and techniques, while not all encompassing, should provide an idea of the types of in-situ metrology operations possible using chromatic confocal probes and other single-point sensors on a range of fabrication platforms.

We present DualSnap, a compact dual-mode, snapshot interferometric on-machine metrology system designed for precision surface form and roughness measurements in single point diamond turning (SPDT). DualSnap integrates laser and LED-based interferometry in a shared optical path and utilizes a pixelated polarization camera for snapshot phase-shifting measurements. This configuration enables rapid, vibration-resilient data acquisition without reconfiguring the optical setup. Integrated directly into SPDT machines, DualSnap provides real-time feedback for tool alignment and process control. Comparative tests on metal and plastic surfaces show excellent agreement with commercial Zygo interferometers, demonstrating its effectiveness and versatility for next-generation optical fabrication.

Design for Excellence (DFX) is a strategic approach that guides key decisions throughout the design process of complex optical systems. The “X” can represent various processes within manufacturing, assembly, cost, or performance. Explore how modular design techniques support assembly, serviceability, and system performance, offering real-world insights into practical implementation, design trade-offs, and system optimization. Applying DFX principles and modular techniques early in development can streamline processes, reduce costs, and elevate overall product quality.

The concept of coaxial deflectometry was introduced at Optifab 2023. Deflectometry is an emerging technique that consists in analyzing the distortion of a grid pattern displayed on a monitor screen which is reflected by the surface under test. From this distortion analysis, the shape of the surface can be obtained with quasi interferometric accuracy. Deflectometry is sensitive to slopes, making the technique highly capable of measuring local defects and mostly insensitive to vibrations, thus releasing the need of a damped optical table. Most important, deflectometry is an absolute measurement, not needing any precise reference part nor CGH. It is why it is specially adapted to the measurement of freeforms. More, its insensitivity to vibrations makes it usable in manufacturing workshops or industrial environments. We present today’s state of the art, showing improved results on parts already presented at Optifab 2023.

Next-generation synchrotron and free-electron laser facilities demand optical components capable of preserving diffraction-limited wavefronts across increasingly challenging photon energy ranges and complex beamline architectures. The beamline performance requirements translate directly into stringent surface specifications: figure errors must be reduced to the sub-nanometer scale, with slope errors below 200 nrad, while maintaining surface roughness at the sub-nanometer level in order to achieve diffraction limited performances and wavefront preservation. This paper describes the work done at NSLS II Optical Metrology Laboratory (Brookhaven National Laboratory) for the development of State of the Art mirror metrology coupled with deterministic polishing processes based on Ion Beam Figuring for the fabrication of Diffraction limited x-ray mirrors.

We present a new spatial integration method for a spatial shearing, heterodyne interferometer capable of measuring aspheric surfaces with high dynamic range, high sensitivity, and low susceptibility to environmental fluctuations. To enable high-accuracy form and mid-spatial frequency measurements, the spatial integration method employs a Power series and Fourier series expansion of the measurement surface. This results in a closed form solution for solving for the original surface, based on the measured phase and the known shear distance across the line sensor used for the measurement. We will show the efficacy of this method on a sample with periodic structures of fixed frequency. The algorithm improves form recovery error with an accuracy as low as ~0.1nm.

This paper investigates the feasibility of measuring form error of all the optical surfaces on a lens in a single setup using a dual tipped diamond stylus. Two lenses were measured with a dual, 2 μm conisphere tipped, diamond stylus on a tactile profilometer having a phase grating interferometer (PGI) gauge. When the lens was mounted in a horizontal orientation, one of the stylus tips was used to measure the optical surface on top of the lens (hereafter referred to as measurement using normal bias), whereas the other stylus tip (180˚ opposite) was used to measure the optical surface on bottom of the lens (hereafter referred to as measurement using reverse bias). To validate the results from the measurement using reverse bias, a given optical surface was measured using both normal bias and reverse bias of the PGI gauge with a suitable fixture. Moreover, this surface was also measured on a LuphoScan instrument, a 3D non-contact profiler based on multiwavelength interferometry, and an average form error profile was extracted from the 3D surface form error map. Surface form was quantified by evaluating peak-to-valley (PV), and root mean square (RMS) parameters to compare the results obtained from measurements using normal bias, reverse bias, and multiwavelength interferometer. It is shown that there is a good agreement not only between normal bias and reverse bias measurements using PGI gauge but also with measurement performed on multiwavelength interferometer. With this additional capability of PGI gauge to measure form error of all the optical surfaces in a single setup, results from both surfaces can be correlated to determine wedge, commonly referred to as inner centration, decenter error between the two surfaces, and thickness of the lens under test.

Substrates with flat, parallel surfaces are generally challenging to characterize optically due to signal artifacts affecting methods like Fizeau interferometry. In addition, spectral properties of the material or eventual coatings of the part, often increase complexity by imposing constraints on the testing wavelength(s). Alternatives, such as contact-based techniques or temporary coatings are unsuitable for fragile, coated parts and hinder quality control. This work presents a one-stop optical platform that combines flexibility and robustness for characterizing plane-parallel optics. Its wavefront sensing approach allows the use of incoherent light, and opens up the choice of test wavelengths matching the requirements of the sample to be tested, while avoiding destructive interference due to unwanted surface reflections. The phase retrieval approach brings significant phase points increase, enabling large optical optics to be tested, while being achromatic on a wide spectral range. We will provide experimental results demonstrating these claims and present transmitted wavefront error, surface shape and material homogeneity measurements performed at multiple wavelengths.

A new stitching interferometer system, OptoMapper, has been developed using an engineered low coherence LED illumination system, where both the spectral and spatial coherence are tailored to allow single surface interference from large plane parallel transparent optical components, without the need to paint the rear surface to suppress interference from that surface. Component applications include optical windows, glass wafers, photomask substrates, etc. The system incorporates precision stages and a downward looking 6 inch aperture interferometer incorporating a low distortion, high spatial resolution optical design, to measure flatness and mid-spatial frequency waviness over a 14 by 14 inch area, producing stitched maps containing over 100 million data points with 35 micron lateral resolution. Bar mirrors of 600 mm by 100 mm can also be measured by utilizing the component loading capability of the X,Y stage offering measurement versatility of larger component size. Uniquely, the system has an integrated reference return mirror enabling measurement of transmitted wavefront error (TWE) of large windows, total thickness variation (TTV) of thin glass wafers as well as homogeneity measurements without oil-on-glass plates with separation of front and back surfaces. The system has a relatively small footprint and is fully motorized with precision motion stages, including motorized tilt-alignment and environmental control, allowing measurement of a 12 inch diameter flat in less than 2 minutes, to subnanometer surface height resolution and repeatability. The system engineering to allow ease-of-use and factors which significantly reduce stitching errors over large areas are discussed along with measurement examples demonstrating the benefit of high spatial resolution mid-spatial frequency analysis for polishing process control.

Radius is a fundamental performance specification of an optical surface. A new method to directly measure radius interferometrically is presented. This new method measures radius simultaneously with surface form at the confocal position. Only one measurement position is required which improves the error budget while removing the requirement for precision mechanics and additional operator training. Measurements are presented here that compare the new Direct RoC method to the industry standard using a Displacement Measuring Interferometer combined with additional mechanics. Comparable measurement uncertainty is demonstrated along with greatly simplified operation.

Elastic Emission Machining (EEM), a deterministic chemical removal process, has been proven to be one of the most effective methodologies for yielding ultra-smooth and ultra-precise optical surfaces. OptiPro has developed a process utilizing this technology in conjunction with the Department of Energy (DOE) and the National Aeronautics and Space Administration (NASA) for the polishing of ultra-precision optical substrates. By determining the proper chemical pairing of polishing slurry mixture and material substrate, OptiPro has been able to deterministically correct and smooth surfaces to < 0.15 nm root mean square (RMS) microroughness, < 5 nm RMS mid-spatial frequency error, and < 50 nm Peak-to-Valley (PV) surface error. This process has also been shown to mitigate support structure print-through on lightweighted optics and yields surfaces without subsurface damage.

The precision optics technology sector requires rapid surface figuring technology that is aligned with both financial and environmental sustainability. The Plasma Figuring technology uses a reactive plasma jet to chemically surface figure optics. The plasma jet is powered by a solid-state microwave generator, which operates at less than 25 W average power: utilizing pulse power mode to reduce the plasma temperature. The ability to discharge a non-thermal plasma at circa 100 ˚C increases the repeatability of the etched Gaussian trenches and maintains the optical surface finish. Plasma Figuring, operating at atmospheric pressure, is designed to create similar figure correction capabilities as Magneto Rheological Finishing (MRF) and Ion Beam Figuring (IBF). Plasma Figuring can achieve high material removal rates with a small spot size; furthermore, it is a technology that uses no harmful chemicals and emits no pollution. Moreover, plasma technology can make optics clean on the atomic level, which potentially can improve the bonding of optics to coatings and improves the Plasma Figuring process. The Satisloh paper presented at the previous Optifab explained the physics and chemistry that underpins this state-of-the-art technology. In this subsequent paper, Corning report figure correction of optical surfaces using the Satisloh Plasma Polisher (SPP). Material removal calculations and rates are presented.

Ion beam machining has a long tradition in the fabrication of classical high-end optical components, enabling deterministic and highly reproducible surface correction on a broad range of optical materials. From sophisticated telescopic assemblies to lithographic projection systems, focused ion beam figuring (IBF) has delivered nanometer-level precision and sub-angstrom micro-roughness for decades. Today, industrial and research environments in precision optics and semiconductors demand not only equal or better optical performance but also markedly higher throughput, consistency, and process resilience. We outline methods for integrating high-resolution beam control with multi-axis motion to achieve productivity and precision concurrently. The result is a future-proof IBF approach capable of addressing both global form and higher-frequency content for next-generation optical and semiconductor applications.

The fabrication of freeform optical components in glass poses significant challenges due to the optical surface’s limited machinability and the complexity of the geometries involved. This study demonstrates the feasibility and advantage of using laser-assisted diamond turning (LADT) to directly machine freeform geometries in optical glass with high precision. Fused silica glass freeform lens geometry was fabricated via LADT, followed by magnetorheological finishing (MRF) to remove subsurface damage (SSD). This technique demonstrates sub 2.5 μm peak-to-valley (PV) form deviation optical surface figure direct from diamond turning. The LADT-fabricated lens exhibited less than 5 μm SSD, which when deterministically removed resulted in sub-nm surface roughness. These findings highlight the potential of LADT as an efficient and high-accuracy approach for manufacturing freeform glass optics.

Since its commercial release in 1997, QED’s MRF^™ technology has been used with great success on a wide array of substrates, especially glass and single crystal materials. Advancements in material science continue to enable new substrates for optical technologies and many of these new materials present manufacturing challenges. We will demonstrate how QED’s MRF^™ technology is uniquely positioned to address these materials, facilitating their intended application through enhancements in removal rate, micro-roughness, and determinism for challenging geometries. Our results pull from several example materials and industry partnerships, highlighting the value in early collaboration to enable effective utilization of the ever-changing optical material solution space.

This study presents a unified closed-form framework for dwell time optimization in precision optical figuring, addressing a critical challenge in computer-controlled optical surfacing (CCOS). The novelty lies in the analytical integration of three previously distinct methods, namely Robust Iterative Fourier Transform Algorithm (RIFTA), Robust Iterative Surface Extension (RISE), and Universal Dwell time Optimization (UDO), into a single mathematical model that supports both function-form and matrix-form formulations. Unlike traditional iterative approaches, the proposed closed-form solutions eliminate the need for numerical optimization, significantly accelerating computation while preserving or improving accuracy.

The chemical composition and oxidation states of SiO₂/Nb₂O₅ multilayer thin films were studied using X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence (XRF). The films were deposited by reactive magnetron sputtering. XPS results showed a partial reduction of niobium from Nb⁵⁺ to Nb⁴⁺ under oxygen-deficient conditions. XRF analysis confirmed an increase in niobium content, indicating a change in film stoichiometry. These findings show that deposition conditions directly affect surface chemistry and element distribution in the films. This study highlights the importance of process control for improving the reliability and performance of dielectric optical coatings.

Reaction-bonded Silicon Carbide (RB-SiC) has emerged as a key material for optical components in space observation systems, owing to its outstanding high specific stiffness and thermal stability, mechanical strength, and chemical resistance. This study presents a comparative analysis of the structural and optical properties of uncoated RB-SiC and CVD-SiCcoated RB-SiC. Comprehensive characterization was performed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and vickers hardness testing. XRD analysis revealed that the CVD-SiC-coated RB-SiC exhibited no residual silicon, indicating high chemical purity, whereas the uncoated RB-SiC showed distinct silicon peaks. The CVD-SiC coating maintained a uniform thickness of approximately 280 μm, with a sharply defined interface and low porosity. The vickers hardness of the coated sample was significantly higher (~3,000 kgf/mm²) compared to that of the uncoated RB-SiC (1,500 ~ 2,000 kgf/mm²). To assess optical performance, both samples were polished to a surface accuracy of λ/4. However, the CVD-SiC-coated RB-SiC showed reduced optical scattering compared to the uncoated RB-SiC, indicating improved optical surface quality.

Laser calorimetry is employed to measure the laser absorption of optical lenses and windows for laser applications. Lower laser absorption in optical lenses extends the lifetime of optical components and enables their use at higher power levels. Since laser absorption in optical lenses predominantly occurs in the surface optical coatings, optical coating technology is crucial for laser optical components. To develop optical coatings with low laser absorption, it is necessary to evaluate the laser absorption of individual thin films that comprise multilayer optical coatings. This study presents a method for evaluating the laser absorption of different optical coating materials through calorimetric measurements of optical components coated with single-layer films. As an example, the laser absorption of ZnS and YbF₃ thin films coated on ZnSe windows was evaluated for CO₂ lasers. Furthermore, the laser absorption was evaluated when applying anti-reflection coatings composed of multilayer films, and the results were compared with the evaluation results of single-layer coatings.

Transparent polycrystalline ZnS can be achieved by Hot-isostatic pressing (HIP) of CVD ZnS. This study employs DOE to quantify how HIP temperature (T), pressure (P), and time (S) affect densification, microstructure, mechanical properties, and optical transmittance from 0.4 to 14 μm. CVD ZnS samples were HIPed following a DOE matrix spanning T, P, S. Densification, grain size, and microstructure were characterized by XRD, and TEM; transmittance and hardness were measured to relate structure to function. Results show temperature as the dominant factor for visible transmittance; pressure and time provide secondary contributions and potential interactions. Densification at high T and P proceeds mainly by plastic deformation, driving grain growth and microstructural evolution. Grain size increases with higher T and longer hold times, correlating with transmittance and hardness; hardness is especially sensitive to temperature due to grain growth. These findings identify the key HIP parameters controlling crystal structure, transmittance, and hardness of ZnS, enabling optimization of ZnS optical lenses with improved visible–IR performance.