This PDF file contains the front matter associated with SPIE Proceedings Volume 10326, including the Title Page, Copyright information, Table of Contents, and Conference Committee listing.

The trend in the optic industry shows, that it is increasingly important to be able to manufacture complex lens geometries on a high level of precision. From a certain limit on the required shape accuracy of optical workpieces, the processing is changed from the two-dimensional to point-shaped processing. It is very important that the process is as stable as possible during the in point-shaped processing. To ensure stability, usually only one process parameter is varied during processing. It is common that this parameter is the feed rate, which corresponds to the dwell time.

In the research project ArenA-FOi (Application-oriented analysis of resource-saving and energy-efficient design of industrial facilities for the optical industry), a touching procedure is used in the point-attack, and in this case a close look is made as to whether a change of several process parameters is meaningful during a processing. The ADAPT tool in size R20 from Satisloh AG is used, which is also available for purchase. The behavior of the tool is tested under constant conditions in the MCP 250 CNC by OptoTech GmbH. A series of experiments should enable the TIF (tool influence function) to be determined using three variable parameters. Furthermore, the maximum error frequency that can be processed is calculated as an example for one parameter set and serves as an outlook for further investigations. The test results serve as the basic for the later removal simulation, which must be able to deal with a variable TIF. This topic has already been successfully implemented in another research project of the Institute for Precision Manufacturing and High-Frequency Technology (IPH) and thus this algorithm can be used.

The next step is the useful implementation of the collected knowledge. The TIF must be selected on the basis of the measured data. It is important to know the error frequencies to select the optimal TIF. Thus, it is possible to compare the simulated results with real measurement data and to carry out a revision. From this point onwards, it is possible to evaluate the potential of this approach, and in the ideal case it will be further researched and later found in the production.

The basic physical measurement principle in DaOS is the vignettation of a quasi-parallel light beam emitted by an expanded light source in auto collimation arrangement. The beam is reflected by the surface under test, using invariant deflection by a moving and scanning pentaprism. Thereby nearly any curvature of the specimen is measurable. Resolution, systematic errors and random errors will be shown and explicitly discussed for the profile determination error. Measurements for a “plano-double-sombrero” device will be analyzed and reconstructed to find out the limit of resolution and errors of the reconstruction model and algorithms. These measurements are compared critically to reference results that are recorded by interferometry and Deflectometric Flatness Reference (DFR) method using a scanning penta device.

The measurement of optical flats, e. g. synchrotron or XFEL mirrors, with single nanometer topography uncertainty is still challenging. At PTB, we apply for this task small-angle deflectometry in which the angle between the direction of the beam sent to the surface and the beam detected is small. Conventional deflectometric systems measure the surface angle with autocollimators whose light beam also represents the straightness reference. An advanced flatness metrology system was recently implemented at PTB that separates the straightness reference task from the angle detection task. We call it ‘Exact Autocollimation Deflectometric Scanning’ because the specimen is slightly tilted in such a way that at every scanning position the specimen is ‘exactly’ perpendicular to the reference light beam directed by a pentaprism to the surface under test. The tilt angle of the surface is then measured with an additional autocollimator. The advantage of the EADS method is that the two tasks (straightness reference and measurement of surface slope) are separated and each of these can be optimized independently. The idea presented in this paper is to replace this additional autocollimator by one or more electro-mechanical tiltmeters, which are typically faster and have a higher resolution than highly accurate commercially available autocollimators. We investigate the point stability and the linearity of a highly accurate electronic tiltmeter. The pros and cons of using tiltmeters in flatness metrology are discussed.

The fabrication of high-quality optical components involves great effort. Polishing often functions as the final step in a manufacturing chain. To reduce the conventionally time-consuming, complex polishing process with loose grain, an interesting approach with novel resin bond grinding tools is presented for surface smoothing. Various processing-experiments were carried out, regarding different silicate materials such as BK7® and fused silica. Among other results it is shown, that good surface qualities with low roughness down to R_a = 8 nm or R_q = 10 nm can be achieved so far, a quality that already allows speaking of “ultra-fine” grinding. This results in remarkable possibilities to reduce conventional fine-machining procedures with loose abrasives. The fine grinded components can directly be polished to finally smooth the surface and remove remaining defects. Total-processing-times can be strongly reduced, involving significant economic advantages.

The current demand of even more powerful and efficient microprocessors, for e.g. deep learning, has led to an ongoing trend of reducing the feature size of the integrated circuits. These processors are patterned with EUV-lithography which enables 7 nm chips [1]. To produce mirrors which satisfy the needed requirements is a challenging task.

Not only increasing requirements on the imaging properties, but also new lens shapes, such as aspheres or lenses with free-form surfaces, require innovative production processes. However, these lenses need new deterministic sub-aperture polishing methods that have been established in the past few years. These polishing methods are characterized, by an empirically determined TIF and local stock removal.

Such a deterministic polishing method is ion-beam-figuring (IBF). The beam profile of an ion beam is adjusted to a nearly ideal Gaussian shape by various parameters. With the known removal function, a dwell time profile can be generated for each measured error profile. Such a profile is always generated pixel-accurately to the predetermined error profile, with the aim always of minimizing the existing surface structures up to the cut-off frequency of the tool used [2].

The processing success of a correction-polishing run depends decisively on the accuracy of the previously computed dwell-time profile. So the used algorithm to calculate the dwell time has to accurately reflect the reality. But furthermore the machine operator should have no influence on the dwell-time calculation. Conclusively there mustn’t be any parameters which have an influence on the calculation result. And lastly it should take a minimum of machining time to get a minimum of remaining error structures. Unfortunately current dwell time algorithm calculations are divergent, user-dependent, tending to create high processing times and need several parameters to bet set.

This paper describes an, realistic, convergent and user independent dwell time algorithm. The typical processing times are reduced to about 80 % up to 50 % compared to conventional algorithms (Lucy-Richardson, Van-Cittert …) as used in established machines. To verify its effectiveness a plane surface was machined on an IBF.

Polishing as a step of the manufacturing process is not only used in the finishing of optical elements made out of glass. An increasing number of applications needs shiny or glossy surfaces. For these parts, the specified roughness has to be achieved by a final polishing step while keeping or improving the final shape.

The goal of the presented research is to predict the material removal that occurs during the polishing process by a simulation based on finite element modelling (FEM). The presented finite element simulation model for PMMA is based on the material parameters for workpiece and polishing tool. Compared to previous research on aspherical elements made out of glass [1], the model allows the description of the process based on material parameters get out the data sheets. The data derived from the finite element modelling is compared with the polishing results on plastic materials (PMMA). Results of the polishing tests compared with the simulated values will be reported.

An increasing part of the optic industry’s added value consists of micro optical components. This increases the demand for effective test methods for micro optics. When conventional test methods are transferred to micro optics, special attention should to be paid to diffraction effects, wave front propagation and precise sample imaging. We show how a well-established tool – the Shack-Hartmann wave front sensor (SHWFS) – which uses a micro lens array as a key element, can be used for testing micro lenses. Different measurement configurations for transmitted light and reflected light testing are discussed. A system which takes advantage of a combination of these test configurations to retrieve information on surface quality, wave front performance, focal length, and defects is presented. Measurement results are shown to demonstrate the system performance.

A Fizeau interferometer is significantly less sensitive to vibrations and air turbulence than other types of interferometers. This is due to the common path of the reference wave front and the object wave front. A common path arrangement offers the opportunity to reduce systematic errors of the measured phase of the surface under test (SUT). That is why Fizeau type interferometers are most commonly used to test e.g. plane surfaces, spheres or aspheres. A reduced uncertainty of the measured phase distribution can be obtained if the reference surface is placed close to the SUT. Multiple beam reflections will produce interference fringes, which are not sinusoidal. Furthermore, the discrete intensity distribution depends on the reflectance of the reference surface and the reflectance of the SUT. Some surfaces to be tested show significant variations of the local reflectance, e.g. lithographic masks with 0.05 ≤ r(x,y) ≤ 0.95. Thus, the inherent potential of phase shifting algorithms cannot be used.

A modification of the reference surface can be applied. An on-axis polarization beam splitter, which is placed in the plane of the reference surface, separates the two surfaces, which are imaged onto the detector. Thus, true two beam interference can be obtained. The potential of phase shifting algorithms can be used. The interference contrast is high, even if large local variations of r(x,y) are present. In addition, high speed operation is enabled. The embodiment of a modified Fizeau type interferometer will be described.

In vibration assisted machining, an additional high-frequency oscillation is superimposed on the kinematics of the conventional machining process. This generates oscillations on the cutting edge in the range of a few micrometers, thereby causing a high-frequency change in the cutting speed or the feed. Consequently, a reduction of cutting forces, an increase of the tool life as well as an improvement of the workpiece quality can be achieved. In milling and grinding it has been shown that these effects are already partially present in the case of a vibration excitation in axial direction relative to the workpiece, which is perpendicular to the cutting direction. Further improvements of the process results can be achieved by superimposing a vibration in cutting direction and thus modifying the cutting speed at high frequency.

The presented work shows the design of an ultrasonic actuator that enables vibration-assisted milling and grinding with ultrasonically modulated cutting speed. The actuator system superimposes a longitudinal torsional ultrasonic oscillation to the milling or grinding tool. It uses a bolt clamped Langevin transducer and a helically slotted horn, which degenerates the longitudinal vibration into a combined longitudinal torsional (L-T) vibration at the output surface. A finite element analysis is used to determine the vibration resonance frequency and mode shapes to maximize the torsional output. Afterwards, the simulation has been experimentally validated.

All systems located in a laboratory environment or factory are subject to disturbances. These disturbances can either come from the surroundings, e.g. floor-induced vibrations, or from the system itself, e.g. stage-induced vibrations. In many cases it is needed to minimize the effect of these disturbances. This can either be done by isolating the system from its disturbance source or by applying damping to the system. In this paper we present various cases in which we have effectively reduced the impact of disturbances on the system’s performance, either by improving its isolation system, by minimizing the impact of stage reaction forces, or by designing polymer damping into the system.

Dressing as an integrated part of the grinding process influences the quality of ground surface and the loading of the grinding tool. This paper addresses the effect of dressing parameters, including the different dressing overlapping ratios (severely high values) and dressing speed ratios (up and down dressing modes) on the chip loading and surface finish in the grinding with micro-pins and grinding wheels with very fine grits. The results revealed that both the ground surface quality and chip loading are significantly influenced by the grinding tool topography which is generated by the dressing process. The very high dressing overlapping ratios generated a fine topography on the grinding tool, which resulted in lower chip loading and finer surface finish. Moreover, both chip nests and welded clogging on the grinding grains were observed. More welded clogging of the grinding pin was detected when the dressing overlapping ratio decreased and down dressing mode was applied. Mirror surface quality (Ra=0.035) was achieved with utilizing overlapping ratios up to 60 for a grinding wheel with grits size #500.

Artificial intelligent and computer simulation are the technological powerful tools for solving complex problems in the manufacturing industries. Additive Manufacturing is one of the powerful manufacturing techniques that provide design flexibilities to the products. The products with complex shapes are directly manufactured without the need of any machining and tooling using Additive Manufacturing. However, the main drawback of the components produced using the Additive Manufacturing processes is the quality of the surfaces. This study aims to minimize the defects caused during Additive Manufacturing with the aid of Artificial Intelligence. The developed AI system has three layers, each layer is trying to eliminate or minimize the production errors. The first layer of the AI system optimizes the digitization of the 3D CAD model of the product and hence reduces the stair case errors. The second layer of the AI system optimizes the 3D printing machine parameters in order to eliminate the warping effect. The third layer of AI system helps to choose the surface finishing technique suitable for the printed component based on the Degree of Complexity of the product and the material. The efficiency of the developed AI system was examined on the functional parts such as gears.

Dynamic metrology holds the key to overcoming several challenging limitations of conventional optical metrology, especially with regards to precision freeform optical elements. We present two dynamic metrology systems: 1) adaptive interferometric null testing; and 2) instantaneous phase shifting deflectometry, along with an overview of a gradient data processing and surface reconstruction technique. The adaptive null testing method, utilizing a deformable mirror, adopts a stochastic parallel gradient descent search algorithm in order to dynamically create a null testing condition for unknown freeform optics. The single-shot deflectometry system implemented on an iPhone uses a multiplexed display pattern to enable dynamic measurements of time-varying optical components or optics in vibration. Experimental data, measurement accuracy / precision, and data processing algorithms are discussed.

The industrial production of components for applications in the area of precision optics has a long-standing tradition in Germany. As in almost all branches of industry, the external circumstances, processes and products have changed over time. Large lots are becoming less frequent and the demand for special components is growing. In order to meet these requirements, it is necessary to adapt the production processes quickly and flexibly. In the field of chemo-mechanical polishing (CMP), this means that in addition to the process parameters such as speed, pressure and feed, the task-specific adaptation of suspension and polishing pad carriers gain in importance. Along with these changes, it is becoming increasingly important to compare and evaluate the properties of the various polishing suspensions. The procedures according to DIN 58750-3 and DIN 58750-4 are suitable for this purpose. Due to the clearly defined procedures and the constant boundary conditions, different suspensions can be compared and evaluated.

The study presented here shows that this method can also lead to misinterpretations. Known relationships, such as the influence of the polishing pad, the concentration of the suspension and the influence of the processed materials play an important role. An extension of the procedure of DIN 58750-3 for the test of a polishing agent can help in a task-specific characterization of polishing slurries.

While setting up grinding processes for optics fabrication, the optimum tool and process parameters have to be chosen. Unfortunately, datasheets of commercial grinding tools contain only information about grit type and size, bond material, tool shape etc., leaving out any information about process parameters to be applied or tool lifetime or performance. For this reason, tools and machining parameters are commonly adjusted during iterative experimental test runs using actual workpieces from production batches which is time consuming, expensive and without guarantee that the optimum set of machining parameters are achieved. In this paper we present a method to determine grinding tools process window for a given workpiece material. That way, ideal machining parameters can be determined offline for maximum reliability and productivity. In addition, the gained data provides the basis to identify the most suitable grinding tool for the desired application.

In this publication the effects, the extent and the importance of the deformation of a workpiece, in particular of lenses, caused by its own weight, before and during the manufacturing process in precision optics are examined. Since the deformations move in the single-digit to two-digit nanometer range, the investigation is carried out in a first step with FEM calculations. This has the advantage that current situations can be quickly interpreted and improved, without having to carry out time-consuming and cost-intensive experiments from the outset. A major part of the work is therefore the investigation of current workpiece holder and clamping situations in optics manufacturing.

The present work concentrates exclusively on the theoretical calculation of the deformations occurring in various clamping situations, which are traced back to reality.

Ansys Workbench is used as a tool for the calculations. The test series under laboratory conditions for the validation of the theoretical results will be part of further work.

The organization of a company needs to refer to the production process and especially to the number of employees. Many enterprises which are growing, are primarily focused on the development of the technology and not on the development of the organization. This ends up in an increase of the turnover but in a reduced margin. For the development of the organization in growing companies there are two things necessary. The development of the staff to work systematically and coordinated in teams as well as the flow of the information and material between the teams.

ERP – systems are required to install the material and information flow especially in the work floor. Unfortunately many enterprises don’t use the ERP-systems to plan and control the material and information flow very detailed. In companies where the control of the material and information flow was installed, it could be demonstrated that the margin increased analog to it. The requirements to the development of the organization based on the increasing number of the employees are basically the same for most of the production processes like the production of metal sheet housings or the production of mirrors and lenses.

In the context of Industrie 4.0, we have previously described the roles of robots in optical processing, and their complementarity with classical CNC machines, providing both processing and automation functions. After having demonstrated robotic moving of parts between a CNC polisher and metrology station, and auto-fringe-acquisition, we have moved on to automate the wash-down operation. This is part of a wider strategy we describe in this paper, leading towards automating the decision-making operations required before and throughout an optical manufacturing cycle.

The commercial availability of automated inspection systems for optical surfaces specified according to ISO 10110-7 promises unsupervised and automated quality control with reproducible results. In this study, the classification results of the ARGOS inspection system are compared to the decisions by well-trained inspectors based on manual-visual inspection. Both are found to agree in 93.6% of the studied cases. Exemplary cases with differing results are studied, and shown to be partly caused by shortcomings of the ISO 10110-7 standard, which was written for the industry standard manual-visual inspection. Applying it to high resolution images of the whole surface of objective machine vision systems brings with it a few challenges which are discussed.

There are many established technologies for precise characterization of the mirror geometries available. The paper presents a high precision measuring setup based on a single beam homodyne laser interferometer. The single beam interferometer is moved by a linear stage between the reference and measuring surfaces and delivers the differences between them. The reference mirror defines an absolute accuracy of the method. This point based method allows a high spatial resolution of the mirror shape and is suitable for measurements of the free form mirror geometries as long as the radius of curvature does not exceed the maximal toleranced tilt.

The measuring results have been obtained for optics with dimensions of up to 50 mm and have been verified both for plan mirrors and for mirrors with radii of curvature in the range between 6 m and 10 m. A repeatability of the measuring results in sub-nanometer range can be shown.

Especially for mirrors with a very big radius of curvature the knowledge of the exact position of the each measuring point on the surface is important for minimizing the errors of the mathematical fitting algorithms. Therefore a triple beam interferometer has been used for measurements of the stage position. The tight synchronization between all interferometer channels of 0.1 ns allows very fast “on-the-fly” scans of the surface.

During polishing of optical surfaces, light scattering from within the sample under test enables on machine monitoring of surface roughness levels during polishing. Surface roughness levels of 0.6 nm rms have been detected and the influence of different pH values of polishing slurries on the surface quality being generated have been monitored. In addition, iIRM’s capability to function as in process contamination control of industrial polishing processes has been demonstrated.