This PDF file contains the front matter associated with SPIE Proceedings Volume 11171 including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

The quality of optical components such as lenses or mirrors can be described by shape errors and surface roughness. With increasing optic sizes, the stability of the polishing process becomes more and more important. Parameters such as chemical stability of the slurry or tool wear are key elements for a deterministic computer controlled polishing (CCP) process. High sophisticated CCP processes such as magnetorheological finishing (MRF) or the ZEEKO bonnet polishing process rely on the stability of the relevant process parameters for the prediction of the desired material removal. Aim of this work is to monitor many process-relevant parameters by using sensors attached to the polishing head and to the polishing process. Examples are a rpm and a torque sensor mounted close to the polishing pad, a vibration sensor for the oscillation of the bearings, as well as a tilt sensor and a force sensor for measuring the polishing pressure. By means of a machine learning system, predictions of tool wear and the related surface quality shall be made. Goal is the detection of the critical influence factors during the polishing process and to have a kind of predictive maintenance system for tool path planning and for tool change intervals.

For Line-Laser sensor products that CCD images are unknown, we present a method for the calibration of Line-Laser sensor measurement system using multi-directional and non-featured planes, and a method for system calibration optimization using multi-angle standard spheres. By building a mathematical model, we convert the line laser sensor measurement data into CMM measurement points. According to the constraint relationships of planes or spheres, the point measured by the Line-Laser sensor and the CMM should conform to the same equation, then we can solve the calibration matrix of the line laser sensor and the coordinate measuring machine by nonlinear optimization. Both simulation analyses and real experiments were conducted. A line laser sensor was used to measure a frosted standard ball with a radius of 12.696 mm. The radius deviation measured by the line laser sensor system and the center deviation of the sphere comparing with the CMM were observed. The experimental results show that the radius deviation of the calibration laser sensor measurement system is less than 0.02mm, and the center distance deviation of the sphere is less than 0.02mm. This method utilizing non-featured planes simplifies the calibration equipment and can reduce the fitting error when using standard ball from multiple angles for calibration. This method is different from the method of calibrating the single direction of the laser sensor. It can simultaneously calibrate the rotation matrix and translation matrix of the two-dimensional line laser sensor to the coordinate measuring machine, and optimize the global optimal calibration parameters.

To meet stringent automotive safety requirements, car taillights typically incorporate retroreflective elements. In addition to their retroreflective role, these structures are also used for lighting/aesthetic/styling purposes. The most common type of automotive retroreflector (RR) – also known as reflex reflector – is characterized by a corner-cube (CC) geometry that has been fabricated for more than 60 years through a conventional pin-bundling technology. While accurate, this manufacturing approach remains time-consuming, expensive and over-constraining in terms of the RR design. To address this, alternate RR fabrication pathways have been developed and this study outlines the capabilities of a novel approach including milestones, setbacks, advantages and disadvantages. Corner-cube geometry includes three mutually orthogonal facets that meet at a common vertex/apex. This configuration precludes the use of most material removal techniques involving rotational tools. To address this, an alternate RR shape called right triangular prism (RTP) was proposed. This geometry is amenable to diamond-based single point cutting approaches, but its optical performance proved to not be identical with that conventional CC RR. The successful fabrication of RTP RRs was demonstrated in acrylic and quality/functionality of the prototype were assessed through both metrological and optical means. Surface quality R_a of less than 20 nm was achieved through an adequate combination of multi-axis machine tool kinematics and ultraprecise single point tool geometry. This cutting technique worked well on non-ferrous, but not on ferrous materials. Nevertheless, an alternative strategy involving micromilling has been developed for cutting RTPs in ferrous substrates. The successful fabrication of tooling inserts has been completed such that injection molded replicas of RTP RRs will be produced in the future. It is expected that the development of cutting-based RR fabrication strategies along with the associate knowledge on the underlying cutting mechanics will enable a broader diversity of RR designs in the future.

In many optical applications plane optical elements are needed for deflection or splitting of light. The functionality of these parts is usually reduced to one certain task and manufacturing of them needs a big amount of effort to achieve high precision. A new optical element is presented, which can fulfill different optical functions simultaneously, is simply built and robust. It is based on glass cuboids joined together under a certain angle while introducing the possibility of fine adjusting the angle in the manufacturing process. The basic components can be modified to offer a lot of different applications. A technological process development is presented as well for more efficient machining of these new parts and existing part geometries. Novel manufacturing processes like ultrasonic grinding, ultrafine grinding and diffusion joining are experimentally investigated, since they promise significant improvements compared to conventional methods. Finally, an appropriate process chain is developed.

This research is focused on the link between manufacturing parameters and the resulting mid-spatial frequency error in the manufacturing process of precision optics. This third publication focuses on strategies of avoidance and generation mechanisms of the mid-spatial frequency errors from the grinding process. The Goal is to understand the generation mechanisms of the mid-spatial frequency errors and avoid their appearance in the manufacturing process.

With more and more industrial devices getting inter-connected the attack surface for cyber attacks is increasing steadily. In this paper the possible approach of an attacker who got access to the office network at the Institute for Precision Manufacturing and High-Frequency Technology (IPH) to attack one of the optic machines that reside in another network segment is presented. Based on known vulnerabilities from the Common Vulnerabilities and Exposures (CVE), like the shellshock exploit or remote code execution with PsExec, for devices identified in the network, an attacker can bypass the firewall between the office network and the laboratory network and get full access to the HMI of the target machine.

Microstructuring of glass optics enables a large variety of benefits for miscellaneous fields of application. From an enhancement of the performance of optical systems to the haptic improvement of coverglasses – the advantages of structured glass are obvious. Especially in the field of high-precision optics, microstructured optical surfaces can carry out important functions, such as beam shaping in laser systems or the correction of dispersive color alterations. Besides enhancements regarding optics of the visible light spectrum, microstructures can compensate disadvantages of infrared(IR)-transmissive lenses such as chalcogenide glasses. As these optics suffer high transmission losses due to their high refractive index the integration of an anti-reflective (AR) function is necessary. Moth-eye-structures are a promising way to avoid the currently used AR-coatings. So far, microstructures are brought into the lens’ surface by lithography mainly. The therefore additional processing step follows the previous shaping. An efficient production of the structured components is the key to success for applications aside science and research. The technology precision glass molding (PGM) is able to combine the contradicting aspects of high precision and high volume production. PGM is a replicative manufacturing method that allows the macroscopic molding and the manufacturing of microscopic structures to be carried out simultaneously. Based on a representative PGM process chain, the paper at hand describes differences, challenges and current research results regarding molding microstructures.

A comparison of two different measurement approaches, a tactile profilometer as well as a non-contact point-probe based metrology system, is conducted. The properties of each approach are highlighted, and measurement results examined.

Plasma Jet Machining is an established process in ultra-precision surface manufacturing. Removal of several nanometers up to millimeters can be achieved using the atmospheric pressure reactive plasma jet as a non-mechanical tool. Surface form measuring techniques have to be improved equally, to further enhance the deterministic machining. Exact knowledge of the instrument transfer function is necessary to distinguish measurement artefacts and reliable measurement results. Precise sinusoidal surface structures prepared by plasma jet etching can be used as calibration elements to determine the instrument transfer function, e.g. slope-measuring devices like Nanometer Optical component measuring Machine (NOM). The steps for manufacturing such calibration elements including theoretical considerations, adjustment of the plasma jet parameters and implementations on different substrates are presented. Finally, a chirped sinusoidal structure on a singlecrystalline silicon slab is fabricated.

Driven by the wide range of applications in the fields of laser technology, biomedicine and consumer electronics, etc., the demand for high-quality lenses with complex geometries and small dimensions is rapidly rising. Since grinding and polishing of such lenses is neither practically nor economically viable, Precision Glass Molding (PGM) has become a popular production method. PGM is a replicative technology for producing high-precision optical lenses in medium or high volumes. During the one-cycle molding process, a glass preform is heated until the viscous state and afterwards pressed into the desired shape using two high-precise molding tools. This process permits the direct and efficient manufacture of high shape accuracy and surface quality optics without any mechanic post-processing step. The efficiency of PGM processes depend primarily on the lifetime of the high-precision molding tools. Therefore, various investigations focus on enhancing the molding tool lifetime. This work focuses on the evaluation of suitable mold materials for PGM, whereby different substrate materials as well as protective coatings are considered. At this, three different kinds of glass with varying molding temperature were investigated: common optical glass, infrared transmissive chalcogenide glass, and fused silica. The molding temperature of common optical glass ranges from 400°C to 700°C, whereas chalcogenide glass is molded at around 250°C. Fused silica requires a more challenging molding temperature of about 1400°C. Due to the varying molding temperatures, different mold materials can be evaluated for each of the investigated glasses.

In the metrology of aspheres and freeforms, missing reference surfaces are a big challenge. The evaluation of the performance of measurement systems is currently done by round robin tests. Since the true form of the used specimens are unknown, the question still remains: who is right? This problem is also faced during the assessment of the performance of the Tilted Wave Interferometer. For both the calibration and measurement complex algorithms are applied. They calculate the system model parameters or the surface error from phaseshifting data. The analytical evaluation of different configurations or the influence of certain errors is impossible. The GUM (Guide to the Expression of Uncertainty in Measurement) proposes Monte Carlo simulations as an option for uncertainty evaluations. They are applicable for complex relationships between a measurand and the system’s input quantities. By repeatedly setting the input quantities to random values within a given range and evaluating the system response, statistically relevant data can be generated. In this contribution we present a Monte Carlo based simulation environment for the performance assessment of non-null interferometric measurements. By using the presented simulation tool, virtual experiments can be executed, including the calibration of the setup. They provide simulated measurement data - in the case of the Tilted Wave Interferometer simulated phase data – taking a number of possible errors, like interferometer errors, stage errors and errors of the reference spheres, into account. On this basis, complete calibration procedures and measurements on given samples can be simulated. Its result can be compared with the simulated truth, since all parameters and errors are known, and a statement about the performance can be made. This tool also proves useful for investigations on effects of measurement parameters such as misalignments of the sample.

High numerical aperture optical elements are relied on for the most demanding applications in optical imaging but pose a significant challenge for conventional metrology techniques. Laser Fizeau interferometers provide a flexible measurement platform for measuring spherical optics by offering a common path configuration to test spherical optics against a convex reference surface. However, in this configuration, traditional piezoelectric transducer (PZT) based phase shifters produce non-uniform phase shifts which vary across the aperture as the spherical reference surface is translated along the optical axis. While these errors are negligible for low numerical aperture optics, the phase shift errors quickly become significant for high numerical aperture optics. The phase shift nonuniformity results in fringe print through and phase ripple artifacts which limit overall accuracy of phase shifted interferometry (PSI) measurements. Spectrally controlled interferometry (SCI) is a method which produces localized, high contrast interference fringes in non-zero optical path length cavities through tailored control of the sources spectral distribution. In addition to fringe location, fringe phase is also controlled through spectrum manipulation without mechanical motion or compensation. As a consequence, the SCI method produces uniform, full-aperture phase shifts with a high degree of linearity regardless of numerical aperture; thus, phase shift errors associated with traditional PZTs can be eliminated. Furthermore, because SCI is a source driven method, it can easily be integrated with any Fizeau interferometer. In this paper, we present the fundamental background for SCI and the advantages of the method as they apply to the measurement of high numerical aperture spherical optics. Additionally, we compare PSI measurements between a traditional laser Fizeau interferometer with PZT based phase shifters and an SCI Fizeau interferometer. Existing methods to this problem are discussed and compared with the presented SCI method, as well.

Accurate measurement of centration of aspheric lenses or even freeforms is a challenge for most devices in optical manufacturing. We are providing a new attempt by combining an autocollimation device and a Vignetting Field Stop [1, 2, 3] device to measure lens centration and sagittal surface profile in a deflectometric approach. Both devices work independently at high accuracy. This presentation explains the technical setup, consisting of an autocollimation sensor (ELWIMAT-AKF) and a Vignetting Field Stop Sensor (ELWIMAT V-SPOT), which is mounted together with an air bearing rotary table in a vertical arrangement. Secondly, we provide the results of the centration measurement and the results from the surface reconstruction and slope error from the measured sagittal angle deviations. Finally, the results from a measured asphere (High Level Expert Meeting HLEM sample #3) is critically discussed to state the accuracy and applicability of the proposed measurement attempt.

In the course of the ever-increasing demand of high-performance optical components, dielectric coating processes are the key technology for the refinement of optics, ensuring their functionality. These optics are based on optical interference coatings, which are formed by a layer stack of alternating transparent single layers of high and low refractive index material. Assuming that turbidity as well as defects embedded in coatings are considered as a primary factor limiting the quality of optical coatings, the level of cleaning the substrates before coating has to be extremely high. Particular importance is attached to the interface between the layer stack and the substrate, especially to the interaction during the transition from the glass surface to the coating during the manufacturing process. This interaction is assumed to be caused by polishing, by corrosion during storage time or by effects during cleaning of the substrate before coating. Thus, it is necessary to characterize each type of defect and to define which technique is adequate to analyze each one of them efficiently. The project aims to raise the awareness and knowledge in terms of what happens during the coating process and, in particular, to understand the physical processes at the substrate during the manufacturing process. After analyzing the material flow, first focus was set on the cleaning procedure. It is assumed that one of the main influences on defects in the interface is the chemical cleaning. Chemical reactions on the surface of the glass substrate may occur due to additional effects of external components and elevated temperature in the washing basins.

Previous work shows the effectiveness of computer controlled polishing (CCP) with the ADAPT tool by Satisloh for correcting form errors in optics manufacturing. This method however has a risk of producing residual errors in the range of mid spatial frequency errors (MSFE). In order to prevent these errors the residual in feed direction is investigated as well as the behavior at different parameters.

Lasers have been known for a long time and are used in a wide variety of fields such as industrial and material processing or measuring and control technology. A new application is being tested which aims to use continuous wave UV-lasers in metrology. For this application a nonlinear optical crystal is needed. Its processing is developed in a two-year project at the Institute for Precision Manufacturing and High-Frequency Technology of Deggendorf Institute of Technology. The crucial factor for the full optical performance in the UV range is the low roughness of the crystal surface, as it is installed between two prisms and the contactability between them should be ensured. In China, a nonlinear crystal that meets the requirements has already been designed and a production process for the raw crystal has been established. However, since the production of optically homogenous crystals has proven to be difficult, the availability of such is very limited. For this reason, a reference material with similar hardness and material behaviour is used in the process development in order not to be limited in the number of trials. It is important to be able to transfer the results from the reference material in an analogous way to the original crystal. One challenge of the project lies in the crystal thickness, since only a maximum thickness of three millimetres can be achieved for the purest form of the crystal required in the application. Therefore, it is important to handle the material sparingly during the process. In addition, the small dimensions of about ten to five millimetres and the brittleness of the material pose a problem. The goal of the project will be to develop a process that can circumvent all these problems so that small roughness of the crystal can be achieved by precision polishing.

This paper provides general information about Magnetic-Abrasive Polishing (MAP) of high-precision surfaces of machines and instruments. The polishing process is performed by a ferroabrasive powder tool, formed by the magnetic field into an “elastic brush”. The magnetic field helps formation of the surface layer with a minimum of structure defects. MAP technologies are used for finishing operations of super-fine polishing of optics, lasers and electronics. The main characteristics of the program-controlled installation of the model A17 for MAP surfaces up to 200 mm in size are presented. The presented effective technology allows forming a surface nanorelief with a roughness parameter Ra of less than 5 angstroms. It allows to significantly increase the laser induced damage threshold of the active elements of optical and laser systems.

Zero point clamping systems are an integral part of the manufacturing industry. They have only yet to find their way into the optical industry. This article compares the hydraulic expansion holder, a clamping system currently used in the optical industry with a zero-point clamping system. The achievable accuracies of both systems are compared over several measurement series. In addition, the process capability evaluation is used for the comparison. Finally, the results are summarized to provide every researcher and practitioner with a foundation for assessing whether zero point clamping systems meet the requirements for the use in optical manufacturing.

An interferometric problem is the limited fringe density, which is due to the limited allowed slope difference of superimposed wave fronts. Thus, the angular dynamic range of measurable surfaces and objects under test is limited. In other words, all shapes that deviate from a plane surface or a sphere represent a measuring problem in interferometers, or require an individually adapted null optics, which might cost e.g. 10 k∈ or more. In addition, ground surfaces cannot be measured in standard interferometers, except by using Speckle interferometry, which is limited in resolution. Freeform optics are very problematic. Even when polished, only tactile or confocal coordinate measurement might work. Several interferometers address the problem of the angular deviation to a sphere. For instance, lateral stitching on a curved surface, which is equivalent to the best-fit sphere, or longitudinal stitching is used. To use a tilted wave interferometer for asphere metrology is another option, which provides versatile measurement configurations. The approach discussed here is to use optical filters. The development of this technique is part of a project most recently started at the Technology Campus in Teisnach. The surface under test (SUT) is imaged onto an optical filter, which has a calibrated angular selectivity. Thus, the angles of the local wave front normal vectors are transferred into an intensity distribution. A set of angular measurements enables reduced uncertainty of the wave front measurement. Aspects as e.g. the working principle, boundary conditions and the identification of practical filters are discussed in the paper.

The Deggendorf Institute of Technology (DIT) and its Faculty of Applied Natural Sciences and Industrial engineering transfer a broad spectrum of knowledge to the students. The clarification of the interrelations that exist between seemingly isolated fields of knowledge is a permanent process. In order to put this into practice, a telescope construction project was started. The base of the in-house student project is the Technology Campus in Teisnach, which bundles capacities for process development, production and measurement of high-precision optics, including telescope optics. A first optical design, which is based on a subset of the parameter space published in 1989 by M. Brunn^{1, 2} (later built by D. Stevick as f/12-system³ ), made use of a primary mirror M1 with a diameter of 400 mm. An f/8-system provide a Strehl ratio SR ≥ 0.8 over an entire field of view of 0.7° deg. Even if this seems to be sufficient, manufacturing tolerances, adjustment tolerances, thermal drift and positional changes considerably reduce the Strehl ratio. In order to obtain reliable values of acceptable tolerances, statistical Monte Carlo analyses had been carried out. As consequences, the tube design was changed and the design of new mirror mounts started. This was done to achieve the required stiffness. The new tube designs, one based on carbon-fiber-reinforced polymer (CFRP) and one based on FeNi36, had been tested by using FEM analysis. In addition, the practicability of deep learning based aberration detection was tested. Zernike polynomials obtained by analyzing the star images with a Convolutional Neuronal Network (CNN). The current state of the development is described.