35 results on '"Wolfram Lyda"'
Search Results
2. Implementation and analysis of an automated multiscale measurement strategy for wafer scale inspection of micro electromechanical systems
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Marc Gronle, Wolfram Lyda, Wolfgang Osten, Avinash Burla, and Tobias Haist
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Engineering ,business.industry ,Mechanical Engineering ,System of measurement ,Real-time computing ,Process (computing) ,Image processing ,Sensor fusion ,Industrial and Manufacturing Engineering ,Automated X-ray inspection ,Feature (computer vision) ,Digital image processing ,Current sensor ,Computer vision ,Artificial intelligence ,Electrical and Electronic Engineering ,business - Abstract
In this contribution the complete implementation of an automated multiscale measurement system (AMMS) for the inspection of micro lenses and micro electromechanical systems is presented. The system uses an adaptable active exploration strategy to balance the conflict between lateral resolution, axial accuracy and measurement duration. It is equipped with several sensors with different fields of view, resolutions and accuracies. The sensors are linked flexibly during the measurement process by image processing and data fusion algorithms. Image processing algorithms are used to identify defect indicators which represent possible unresolved defects in the current sensor scale. The information, gathered by the indicator algorithms, results in new regions of interest and knowledge about the specimen feature which is needed to select and to condition more finely scaled sensors, and to trigger higher resolved measurements in the next scale. For the automated adaption and parameter optimization of the system to a measurement task, an assistant system for sensor and algorithm selection is used. We present the necessary components for automatic task adaptation and active exploration of micro lenses and micro electromechanical systems (MEMS). Inspection results for MEMS-wafer and micro lens arrays and a performance analysis are discussed.
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- 2012
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3. Verlässlichkeitsanalyse von Indikator-Funktionen in einem Automatisierten Multiskalen-Messsystem
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Oliver Sawodny, Engelbert Westkämper, Johan Regin, Wolfram Lyda, Wolfgang Osten, Avinash Burla, Jan Zimmermann, and Publica
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Automated Multiscale Measuring System (AMMS) ,Algorithmus ,Messsystem ,Messsystemanalyse ,Computer science ,Indikator ,Zuverlässigkeit ,Messen ,Electrical and Electronic Engineering ,Instrumentation ,Sensor - Abstract
Zusammenfassung Innerhalb automatisierter multiskaliger Messsysteme werden im Allgemeinen verschiedene Sensoren in verschiedenen Skalen zur Vermessung/Inspektion verwendet. Ausgehend von der niedrigstauflösenden Skale werden Indikationen für Defekte mittels Indikatoralgorithmen gefunden. Basierend auf diesen Defektindikationen werden Unterregionen für eine Vermessung mit höherer Auflösung spezifiziert. Dieser Vorgang wird iterativ bis zur klaren Defekterkennung durchgeführt. Grundlage einer entsprechenden Vorgehensweise ist die Verwendung zuverlässiger Indikatoralgorithmen. Entsprechende Algorithmen für die Vermessung von Mikrooptiken werden vorgestellt und hinsichtlich ihrer Zuverlässigkeit analysiert.
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- 2010
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4. Model-Based Control of a High-Precision Measurement Machine for Multiscale Inspection Tasks
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Wolfgang Osten, Jan Zimmermann, Wolfram Lyda, and Oliver Sawodny
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Engineering ,Scale (ratio) ,Position (vector) ,business.industry ,Control theory ,Linearization ,System of measurement ,Trajectory ,Estimator ,Workspace ,business ,Residual ,Simulation - Abstract
Quality inspection of micro systems on wafer scale must cope with opposing demands: nanometre accuracy and high velocity in a comparatively large workspace. An Automated Multiscale Measurement System (AMMS) combines multiple sensors that operate at specific scales by an intelligent measurement strategy in order to balance speed and accuracy. The AMMS demonstrator is based on a modified Mahr MFU100 with a position and tilt measurement resolution of 1 nm. In this paper multiscale models of a horizontal linear axis with an operating range of 200 mm and their application to state linearization and control parameterization of the residual dynamics are developed and discussed. Main modeling issues are sliding and submicron presliding friction for model-based control, reaching from submicron positioning to high-velocity trajectory tracking with desired performance. Therefore, sliding friction parameters and the friction state of an elasto-plastic friction estimator are adapted online. Experimental results show the effectiveness of the approach for fast submicron and large scale positioning.
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- 2010
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5. Fusion multimodaler Daten am Beispiel eines Mikrolinsen-Arrays (Multimodal Data Fusion Exemplified on a Microlens Array)
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Albert Weckenmann, Wolfram Lyda, Andreas Tünnermann, Jan Zimmermann, Philipp Krämer, Angela Duparré, Andreas Staude, Axel Kranzmann, Sven Schröder, Martin Ritter, Jürgen Goebbels, Engelbert Westkämper, Oliver Sawodny, Wolfgang Osten, and Johan Regin
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Microlens ,Engineering drawing ,Engineering ,Fusion ,business.industry ,Multimodal data ,Computer graphics (images) ,Electrical and Electronic Engineering ,business ,Instrumentation - Abstract
Die Zusammenführung von Messinformationen aus verschiedenen Verfahren ermöglicht eine einheitliche und umfassende Charakterisierung von 3D-Geometrien und deren Kenngrößen. Es werden Methoden zur Verarbeitung, Vereinigung und Auswertung von multimodalen und multiskaligen Messdaten vorgestellt und anhand beispielhafter Messungen konkretisiert. Ein eingesetzter Probenkörper, basierend auf einem Mikrolinsenarray, wird mittels taktiler, konfokaler, interferometrischer Verfahren sowie Röntgentomographie und Streulicht untersucht. Anhand der resultierenden Messdatensätze werden Rauheitsspektren berechnet und diese wiederum zu einem gemeinsamen Rauheitsspektrum des Probenkörpers fusioniert. Nach der Registrierung der Datensätze mittels einer Pyramidenstruktur und Referenzmarken wird ein multimodaler Vergleich der verwendeten Messgeräte möglich.
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- 2008
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6. itom: an open source metrology, automation, and data evaluation software
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Wolfram Lyda, Wolfgang Osten, Christian Kohler, Marc Gronle, and Marc Wilke
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Rapid prototyping ,Hardware architecture ,Software suite ,business.industry ,Computer science ,computer.software_genre ,Automation ,Atomic and Molecular Physics, and Optics ,Software framework ,Optics ,Software ,Embedded system ,Digital image processing ,Electrical and Electronic Engineering ,business ,Engineering (miscellaneous) ,computer - Abstract
Modern optical sensors and measurement systems usually are a powerful combination of optical elements, active hardware components like actuators or sensing devices as well as a sophisticated control software and data evaluation algorithms. In order to develop and operate such systems, it is necessary to have a flexible, intuitive, and fast underlying software framework that also allows for rapid prototyping of a sensor in a dynamic lab environment. This software must be able to control and communicate with all necessary hardware devices and has to provide all the highly performant evaluation, data, and image processing algorithms required. In this publication, we want to present the open source measurement and data evaluation software suite itom, which has been designed considering the denoted requirements and whose development began in 2011.
- Published
- 2014
7. Automated Multi-sensor Inspection of 3D Objects
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Wolfram Lyda, Marc Gronle, and Wolfgang Osten
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Visual inspection ,Automated X-ray inspection ,Computer science ,business.industry ,Feature (computer vision) ,Remote visual inspection ,Computer vision ,Artificial intelligence ,Object (computer science) ,business ,Critical dimension ,Structured-light 3D scanner ,Multi sensor - Abstract
Considering modern manufacturing processes, there is an increasing demand for flexible, fast and precise inspection systems. An inspection can for instance consist of the verification of the geometrical form of the object or the detection of undesired surface features, like scratches, dents or bumps. All in all, an appropriate inspection system must comply with two main requirements: On the one hand, any part of the three-dimensional surface of the object must be examined with respect to a lot of different specifications, which often requires different, adapted measurement techniques and sensors. On the other hand, the inspection has to be done on large areas whereas the critical dimension of any feature may be much smaller.
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- 2014
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8. Object Depending Measurement Uncertainty of Confocal Sensors
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Florian Mauch, Wolfgang Osten, and Wolfram Lyda
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Physics ,Microscope ,medicine.diagnostic_test ,business.industry ,Confocal ,law.invention ,Numerical aperture ,Interferometry ,Optics ,Optical coherence tomography ,Confocal microscopy ,law ,Microscopy ,medicine ,business ,Coherence (physics) - Abstract
Confocal gating is a very efficient tool to restrict light reaching the detector of an optical sensor to a certain volume. In fact, it was invented to facilitate imaging inside biological, strongly scattering media [1]. From there on a number of different sensor implementations relying on confocal gating were developed and so called confocal microscopes have been used extensively in many kinds of applications [2]. Meanwhile their popularity is so high, that confocal microscopy has been put on Natures list of milestones in light microscopy [3]. In classic confocal sensors, imaging is achieved by mechanically scanning the measurement object in axial direction relative to one or several optical measurement spots in parallel [4, 5]. This mechanical, axial scan has been replaced later by a spectral distribution of the measurement spot in axial direction both for point sensors [6] and areal sensor configurations [7]. More recently this chromatic confocal measurement principle has been combined with spectral interferometry in order to achieve a more constant lateral resolution over the measurement range while retaining an interferometric axial resolution [8]. Also it was realized recently that even in measurement systems, that utilize coherence gating [9], confocal gating is inherent and has to be taken into account [10]. Furthermore, it was shown that by properly aligning the properties of the coherence and the confocal gating, resolving power of coherence gating sensors can be improved [11].
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- 2014
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9. itom – An Open Source Measurement, Automation and Evaluation Software Suite
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Wolfgang Osten, Christian Kohler, Marc Gronle, Wolfram Lyda, Marc Wilke, and Heiko Bieger
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Set (abstract data type) ,Rapid prototyping ,Data processing ,Focus (computing) ,Software suite ,Software ,business.industry ,Computer science ,Embedded system ,System of measurement ,business ,Software engineering ,Automation - Abstract
Both the development of new optical sensors including overall measurement systems and the operation of such systems require a fast and flexible underlying software. This software has to be able to control and communicate with a wide range of different hardware systems, such as cameras or actuators, while providing as diversified and complete as possible a set of evaluation and data processing methods. Additionally, the rapid prototyping of such systems requires a software, where parameters or components can easily be changed at runtime while retaining the above focus on fast hardware access and high computational performance.
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- 2014
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10. Making, testing, applying: some progress in the field of micro-optics at ITO
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Goran Baer, René Reichle, Woflgang Osten, Wolfram Lyda, Matthias Häfner, Christof Pruss, and Frederik Schaal
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Data processing ,Materials science ,Optics ,business.industry ,Process (engineering) ,Information processing ,New materials ,Optical metrology ,business ,Maskless lithography ,Field (computer science) ,Manufacturing engineering ,Metrology - Abstract
Microoptical components play an increasing role in different technology fields such as medical engineering, materials and information processing, imaging and metrology. But their realization needs the combination of modern design concepts with sophisticated processing technologies, new materials and design tools. Furthermore, the introduction of ambitious processing technologies must be accompanied by effective metrology and inspection tools. Therefore, this paper reports about the technologies for making microoptics at ITO. Because sophisticated measurement tools are an indispensable part of the fabrication process, the paper describes our multi-scale inspection approach for the testing of microstructures on wafer-scale level. Finally, some representative applications of microoptical components for advanced measurement and imaging are explained.
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- 2013
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11. Robust signal evaluation for Chromatic Confocal Spectral Interferometry
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Wolfram Lyda, Tobias Boettcher, Marc Gronle, Florian Mauch, and Wolfgang Osten
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Interferometry ,Wavelet ,Materials science ,Optics ,Surface metrology ,business.industry ,Confocal ,Measuring principle ,Chromatic scale ,business ,Signal ,Envelope (waves) - Abstract
The hybrid measurement principle Chromatic Confocal Spectral Interferometry combines Spectral Interferometry with Chromatic Confocal Microscopy and therefore benefits from their respective advantages. Our actual demonstrator setup enables an axial measurement range up to 100 μm with resolution up to 5 nm depending on the employed evaluation method and the characteristics of the object’s surface. On structured surfaces, lateral features down to 1 μm can be measured. As the sensor raw signal consists of a Spectral Interferometry type wavelet modulated by a confocal envelope, two classes of evaluation methods working on the phasing or the position of the envelope are employed. Even though both of these information channels are subject to their respective problems, we show that a proper combination of the individual methods leads to a robust signal evaluation. In particular, we show that typical artifacts on curved surfaces, that are known from Chromatic Confocal Microscopy, are minimized or completely removed by taking the phasing of the Spectral Interferometry wavelet into consideration. At the same time the problem of determining the right fringe order of the Spectral Interferometry signal at surface discontinuities can be solved by evaluation of the confocal envelope. We present here a first approach using a contrast threshold on the signal and a median referencing for trusted sections of the analysed topography, which yields a reduction of artifacts in a submicron range on steep gradients, discontinuous specimen or curved mirror-like surfaces.
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- 2013
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12. Model-based, active inspection of three-dimensional objects using a multi-sensor measurement system
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Wolfgang Osten, Wolfram Lyda, and Marc Gronle
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Automated optical inspection ,Engineering ,Automated X-ray inspection ,Transformation (function) ,Data acquisition ,business.industry ,System of measurement ,Coordinate system ,Process (computing) ,Initialization ,Computer vision ,Artificial intelligence ,business - Abstract
Considering modern manufacturing processes, there is an increasing demand for flexible, fast and precise inspection systems. Usually, the holistic inspection of technical components with a complex three-dimensional surface, like gears, needs to be separated into inspection steps. Different areas on the object need to be verified with respect to varying characteristic specifications, e.g. related to defects or roughness properties. Such manifold inspection tasks can for instance be realized using a multi-sensor measurement system which is also equipped with a multi-axis system to optimally move and rotate each sensor with respect to any desired position at the object’s surface. In order to generate an automatic inspection system, the entire process is defined with respect to a polygonal model of the measurement specimen, such that different sub-regions are connected with different specifications and parameterizations that this region must meet and hence needs to be verified by the inspection system. However, the data acquisition with respect to sub-regions on the model’s surface and the integration of obtained datasets in the model’s coordinate system is only feasible if the transformation of the real object to the model is determined before. Consequently, this needs to be determined in the initialization phase of the overall inspection process.
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- 2013
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13. Improved signal model for confocal sensors accounting for object depending artifacts
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Florian, Mauch, Wolfram, Lyda, Marc, Gronle, and Wolfgang, Osten
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Equipment Failure Analysis ,Microscopy, Confocal ,Image Interpretation, Computer-Assisted ,Computer-Aided Design ,Reproducibility of Results ,Computer Simulation ,Equipment Design ,Models, Theoretical ,Artifacts ,Image Enhancement ,Sensitivity and Specificity ,Algorithms ,Lenses - Abstract
The conventional signal model of confocal sensors is well established and has proven to be exceptionally robust especially when measuring rough surfaces. Its physical derivation however is explicitly based on plane surfaces or point like objects, respectively. Here we show experimental results of a confocal point sensor measurement of a surface standard. The results illustrate the rise of severe artifacts when measuring curved surfaces. On this basis, we present a systematic extension of the conventional signal model that is proven to be capable of qualitatively explaining these artifacts.
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- 2012
14. Extrinsic calibration of a fringe projection sensor based on a zoom stereo microscope in an automatic multiscale measurement system
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Marc Gronle, Wolfram Lyda, Wolfgang Osten, and Avinash Burla
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Computer science ,business.industry ,System of measurement ,Coordinate system ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Point cloud ,Structured-light 3D scanner ,Data set ,Position (vector) ,Stereo microscope ,Calibration ,Computer vision ,Artificial intelligence ,Zoom ,business ,Remote sensing - Abstract
Multi scale systems offer the opportunity to balance the conflict between execution time, measurement volume and resolution for the inspection of highly complex surface profiles. An example of such a task is the inspection of gears. At first, the coarse position and form of the specimen is registered by a sensor measuring with comparatively low resolution but a large field of view. Possible defects near to the resolution limit are indicated and new regions of interest for higher resolved measurements are identified. As prerequisite for a successful multi-scale inspection, every sampled data set, acquired in different scales and at varying positions, must be registered in one global data model. This is only possible if the extrinsic coordinate transform from the sensor's internal coordinate system to the common, global coordinate system of the inspected object and its uncertainties are known. In this paper, we present an approach for the extrinsic calibration using the example of a multi-zoom fringe projection sensor mounted on a multi-axes measurement system. Finally we show the measurement result of a gear, where several sampled patches are merged together into one point cloud with the aid of the presented calibration.
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- 2012
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15. Multilevel optical sectioning based on digital holography with a femtosecond frequency comb laser
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Tilo Steinmetz, Ronald Holzwarth, Wolfgang Osten, Giancarlo Pedrini, Klaus Körner, Wolfram Lyda, and Igor Alexeenko
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Materials science ,Optical sectioning ,business.industry ,Holography ,Physics::Optics ,Curved mirror ,Laser ,law.invention ,Frequency comb ,Optics ,law ,Fiber laser ,Digital holographic microscopy ,business ,Digital holography - Abstract
In this paper, we demonstrate how short coherence digital holography with a pulsed fiber laser frequency comb may be used for multi-level optical sectioning. For the proof of the principle, a conic object having a size of few centimeters is used. The object shape is obtained by digitally reconstructing and processing a sequence of holograms recorded during stepwise shifting of a spherical mirror in the reference arm of the holographic set-up. First experimental results are presented.
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- 2012
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16. 4.3.1 Herausforderungen und Lösungsansätze für die fertigungsnahe Qualitätskontrolle mittels optischer 3D-Messtechnik
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Wolfram Lyda, D. Fleische, Klaus Körner, Marc Gronle, Florian Mauch, and Wolfgang Osten
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Materials science - Published
- 2012
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17. Automated alignment of aspheric and freeform surfaces in a non-null test interferometer
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Wolfgang Osten, Christof Pruss, Goran Baer, Wolfram Lyda, and Eugenio Garbusi
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Surface (mathematics) ,Interferometry ,Engineering ,Optics ,Null (radio) ,Test beam ,business.industry ,Plane (geometry) ,Astronomical interferometer ,Phase (waves) ,business - Abstract
An automatic method for the positioning of a test surface in a non-null interferometer is presented. If the test surface is positioned incorrectly with respect to the test beam this leads to aberrations, which distort the measurement of the surface. A central issue in the interferometric characterization of surfaces is to avoid aberrations due to an incorrect placement of the test surface. In case of spherical and plane surfaces these errors can usually be distinguished from the surface figure errors and are eliminated in post processing. For aspheric and free-form surfaces this task is no longer trivial. Therefore it is important to minimize the alignment error of the surface. In this work the effect on the measured phase due to lateral and axial displacements of the aspheric surface is calculated and an adjustment method for the positioning of the surface at a predefined measurement location is presented. Experimental results showing the feasibility of the proposed procedure are presented.
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- 2011
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18. Assistant systems for efficient multiscale measurement and inspection
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Wolfram Lyda, Mohamed Hassanine Aissa, Wolfgang Osten, Avinash Burla, and Tobias Haist
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Engineering ,Artificial neural network ,business.industry ,System of measurement ,Process (computing) ,Object (computer science) ,Sensor fusion ,Software ,Computer engineering ,Component-based software engineering ,Digital image processing ,Computer vision ,Artificial intelligence ,business - Abstract
Optical inspection systems constitute hardware components (e.g. measurement sensors, lighting systems, positioning systems etc.) and software components (system calibration techniques, image processing algorithms for defect detection and classification, data fusion, etc.). Given an inspection task choosing the most suitable components is not a trivial process and requires expert knowledge. For multiscale measurement systems, the optimization of the measurement system is an unsolved problem even for human experts. In this contribution we propose two assistant systems (hardware assistant and software assistant), which help in choosing the most suitable components depending on the task considering the properties of the object (e.g. material, surface roughness, etc.) and the defects (e.g. defect types, dimensions, etc.). The hardware assistant system uses general rules of thumb, sensor models/simulations and stored expert knowledge to specify the sensors along with their parameters and the hierarchy (if necessary) in a multiscale measurement system. The software assistant system then simulates many measurements with all possible defect types for the chosen sensors. Artificial neural networks (ANN) are used for pre-selection and genetic algorithms are used for finer selection of the defect detection algorithms along with their optimized parameters. In this contribution we will show the general architecture of the assistant system and results obtained for the detection of typical defects on technical surfaces in the micro-scale using a multiscale measurement system.
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- 2011
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19. Conceptual consideration for the process integration of optical sensors
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David Fleischle, Wolfgang Osten, Florian Mauch, and Wolfram Lyda
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Engineering ,Measure (data warehouse) ,business.industry ,System of measurement ,media_common.quotation_subject ,Control engineering ,Work in process ,Variety (cybernetics) ,Task (project management) ,Process integration ,Measurement uncertainty ,Quality (business) ,business ,media_common - Abstract
In manufacturing monitoring and inspection is an essential task to maintain a high product quality. Therefore a variety of systems (e.g. tactile systems, acoustic systems, optical systems,...) is used. However there is still a lack in controlling the product quality near the production machine. For the selection and the design of an appropriate monitoring strategy the specification of the applied sensors is of crucial importance. Optical sensors are in general suitable to measure quality relevant features. But they are often not robust enough, to use them in harsh environments such as the workshop floor. However to detect as early as possible if quality runs out off specification, the high resolution of optical measurement systems is often not needed. In these cases optical sensors can be implemented successfully even if their measurement uncertainty is increasing due to the harsh environment. To verify this hypothesis an evaluation of environmental influences has to be made and a comparison between the acceptable and still achieveable measurement uncertainty has to be made. For this reason a conceptual consideration regarding optical sensors developed for in-process monitoring is presented. The focus will be on the investigation of the influence of the environment on the measurement result, and on strategies how these can be estimated. Based on this an appropriate design and construction of the sensor system can be obtained.
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- 2011
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20. Combining rigorous diffraction calculation and GPU accelerated nonsequential raytracing for high precision simulation of a linear grating spectrometer
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Wolfram Lyda, Reto Häring, Florian Mauch, Wolfgang Osten, Torsten Krug, and David Fleischle
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Diffraction ,Spectrometer ,business.industry ,Computer science ,Stray light ,Physics::Optics ,Grating ,Superposition principle ,Optics ,Physics::Atomic Physics ,Monochromatic color ,business ,Rigorous coupled-wave analysis ,Light field - Abstract
Simulation of grating spectrometers constitutes the problem of propagating a spectrally broad light field through a macroscopic optical system that contains a nanostructured grating surface. The interest of the simulation is to quantify and optimize the stray light behaviour, which is the limiting factor in modern high end spectrometers. In order to accomplish this we present a simulation scheme that combines a RCWA (rigorous coupled wave analysis) simulation of the grating surface with a selfmade GPU (graphics processor unit) accelerated nonsequential raytracer. Using this, we are able to represent the broad spectrum of the light field as a superposition of many monochromatic raysets and handle the huge raynumber in reasonable time.
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- 2011
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21. Interferometrische Messung von Freiform-Schneidkanten auf einer Diamantwerkzeug-Bearbeitungsmaschine
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David Fleischle, Reinhard Berger, Christian Brecher, Andreas Sobotka, Wolfgang Osten, Christian Wenzel, Klaus Körner, Wolfram Lyda, and Publica
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White light interferometry ,Materials science ,Optics ,business.industry ,Electrical and Electronic Engineering ,business ,Instrumentation ,Diamond tool - Abstract
Durch den Einsatz von optischer Topografiemesstechnik mit sehr hoher axialer Auflösung auf der neu entwickelten Diamantbearbeitungsmaschine ist es möglich, die geometrischen Begrenzungen bei der Endbearbeitung von hochgenauen Diamantwerkzeugen zu überwinden. Im Vergleich zu der oftmals eingesetzten digitalen Bildverarbeitung wird das Diamantwerkzeug bei der Weißlichtinterferometrie senkrecht angemessen. Nur so kann die hohe axiale Auflösung der Interferometrie zur Bestimmung der Schneidengeometrie genutzt werden. Erste Messungen zeigen die Vorteile der Integration der optischen Messtechnik auf der Maschine. Durch eine Zusatzbeleuchtung für das Diamantwerkzeug konnten darüber hinaus die Vorteile der Bildverarbeitung für die Formmessung nutzbar gemacht werden, so dass ein hybrides Messsystem zur Verfügung steht. Die mit dem neu entwickelten Maschinensystem gefertigten und mit der maschinenintegrierten Messtechnik geprüften Werkstücke müssen in einer weiteren Etappe durch hochauflösende Referenzmesstechnik im Labor verifiziert werden. Dazu sollen ein stationäres Weißlichtinterferometer hoher lateraler Auflösung und ein Rasterkraftmikroskop (AFM) eingesetzt werden.
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- 2011
22. Optical metrology: from the laboratory to the real world
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René Reichle, C. Falldorf, Wolfgang Osten, Christof Pruss, Eugenio Garbusi, David Fleischle, and Wolfram Lyda
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Factory floor ,Engineering drawing ,Interferometry ,Engineering ,Shearography ,business.industry ,System of measurement ,Stability (learning theory) ,Systems engineering ,Sensitivity (control systems) ,Optical metrology ,business ,High potential - Abstract
Optical metrology has shown to be a versatile tool for the solution of many inspection problems. The main advantages of optical methods are the noncontact nature, the non-destructive and fieldwise working principle, the fast response, high sensitivity, resolution and accuracy. Consequently, optical principles are increasingly being considered in all steps of the evolution of modern products. However, the step out of the laboratory into the harsh environment of the factory floor was and is a big challenge for optical metrology. The advantages mentioned above must be paid often with strict requirements concerning the measurement conditions and the object under test. For instance, the request for interferometric precision in general needs an environment where high stability is guaranteed. If this cannot be satisfied to a great extent special measures have to be taken or compromises have to be accepted. But the rapid technological development of the components that are used for creating modern optical measurement systems, the unrestrained growth of the computing power and the implementation of new measurement and inspection strategies give cause for optimism and show that the high potential of optical metrology is far from being fully utilized. In this article current challenges to optical metrology are discussed and new technical improvements that help to overcome existing restrictions are treated. On example of selected applications the progress in bringing optical metrology to the real world is shown.
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- 2010
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23. Rapid ideal template creation for the inspection of MEMS based on self-similarity characteristics
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Anto Yesuadimai Michael, Tobias Haist, Wolfram Lyda, Wolfgang Osten, and Avinash Burla
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Digital image ,Similarity (geometry) ,Sum of absolute differences ,business.industry ,Surface metrology ,Computer science ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,Computer vision ,Image processing ,Artificial intelligence ,Image segmentation ,business ,Feature detection (computer vision) - Abstract
Surface metrology of MEMS requires high resolution sensors due to their fine structures. An automated multiscale measurement system with multiple sensors at multiple scales enables fast acquisition of the surface data by utilizing high resolution sensors only at locations required. We propose a technique that depends on the fact that often MEMS have features (e.g. combs) repeating across the surface. These features can be segmented and fused to generate an ideal template. We present an automated similarity search approach based on feature detection, rotation invariant matching, and sum of absolute differences to find similar structures on the specimen. Then, similar segments are fused and replaced in the original image to generate an ideal template.
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- 2010
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24. An assistance system for the selection of sensors in multi-scale measurement systems
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Wolfgang Osten, Avinash Burla, Tobias Haist, and Wolfram Lyda
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Computer science ,System of measurement ,Resolution (electron density) ,Electronic engineering ,Scale measurement ,Selection (genetic algorithm) ,Remote sensing ,Structured-light 3D scanner - Abstract
Optical inspection using multi-sensor multi-scale systems requires the selection of proper sensors, their parameters (e.g. resolution, N.A, lighting conditions), and measurement strategies. We propose an assistance system that automatically selects the suitable sensors and their parameters for an inspection specification. The specimen and the defects are described based on their properties (e.g. geometry, material etc) to the assistance system. The system then uses different "sub-assistants", each designed for a specific measurement technique, to recommend the most suitable measurement setups. The system and initial results for fringe projection techniques are presented.
- Published
- 2010
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25. Optical metrology for process control: modeling and simulation of sensors for a comparison of different measurement principles
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Wolfgang Osten, Wolfram Lyda, Florian Mauch, and David Fleischle
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Computer science ,business.industry ,System of measurement ,Measure (physics) ,law.invention ,Modeling and simulation ,Interferometry ,Optics ,Confocal microscopy ,law ,Microscopy ,Electronic engineering ,Process control ,Point (geometry) ,Focus (optics) ,business - Abstract
To increase the quality of future products and decrease the manufacturing cost at the same time a systematic control of the fabricated objects is necessary. A promising approach for inline quality control of surface and form parameters is the use of optical measurement systems. This is due to the non-destructive nature of the optical measurement techniques. But in the production environment there are many challenges to overcome for optical sensors. Examples are temperature fluctuation, vibrations, fluids on the object surface and rough surfaces. Therefore, it is likely that not all optical measurement methods are suitable for that task. Hence, a classification of the different principles is necessary with the objective to identify the most appropriate measurement approach for a particular inspection task. In this contribution we start with a systematic approach for a review of sensors within production systems. Then we concentrate on the most robust class of optical sensors, the point sensors. In order to minimize the effect of mechanical vibrations it is desirable to employ measurement techniques that are able to measure the height of an object point in a very short time. Therefore, we focus in this work on chromatic-confocal microscopy and spectral interferometry. The aim is to compare these measurement methods for their ability to cope with the challenges given by the production environment in general. To this end we will develop simulation models for the mentioned techniques and compare two exemplarily sensors for their capability to be used for process control.
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- 2010
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26. Chromatic confocal spectral interferometry for technical surface characterization
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Tobias Haist, David Fleischle, Wolfram Lyda, and Wolfgang Osten
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Materials science ,business.industry ,Confocal ,Surface finish ,law.invention ,Modeling and simulation ,Interferometry ,Optics ,Confocal microscopy ,law ,Astronomical interferometer ,Surface roughness ,Chromatic scale ,business - Abstract
Chromatic confocal spectral interferometry (CCSI) is a hybrid method for fast topography measurement, which combines the advantages of the interferometric gain and accuracy with the robustness of confocal microscopy. The CCSI-principle provides a single shot measurement of depth while offering a higher lateral resolution than commonly used spectral interferometers. This contribution is focused on the modeling and simulation of a CCSI-sensor for measuring rough surfaces, based on sequential and non-sequential ray-tracing. With the simulation, the influence of surface roughness, surface reflectivity, and surface contamination on reliability of the sensor can be estimated.
- Published
- 2009
- Full Text
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27. Automated Multiscale Measurement System for micro optical elements
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Tobias Haist, Wolfgang Osten, Avinash Burla, Wolfram Lyda, Jan Zimmermann, and Oliver Sawodny
- Subjects
Point spread function ,Microlens ,Optics ,business.industry ,Computer science ,System of measurement ,Fourier descriptor ,business - Published
- 2009
- Full Text
- View/download PDF
28. Open-source graphics processing unit–accelerated ray tracer for optical simulation
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Wolfgang Osten, Wolfram Lyda, Marc Gronle, and Florian Mauch
- Subjects
Geometrical optics ,Computer science ,Computer graphics (images) ,General Engineering ,Graphics processing unit ,Ray tracing (graphics) ,Graphics ,Ray ,Atomic and Molecular Physics, and Optics ,Beam tracing ,Distributed ray tracing ,Visualization - Abstract
Ray tracing still is the workhorse in optical design and simula- tion. Its basic principle, propagating light as a set of mutually independent rays, implies a linear dependency of the computational effort and the num- ber of rays involved in the problem. At the same time, the mutual independ- ence of the light rays bears a huge potential for parallelization of the computational load. This potential has recently been recognized in the visualization community, where graphics processing unit (GPU)-acceler- ated ray tracing is used to render photorealistic images. However, preci- sion requirements in optical simulation are substantially higher than in visualization, and therefore performance results known from visualization cannot be expected to transfer to optical simulation one-to-one. In this contribution, we present an open-source implementation of a GPU-accel- erated ray tracer, based on nVidias acceleration engine OptiX, that traces in double precision and exploits the massively parallel architecture of modern graphics cards. We compare its performance to a CPU-based tracer that has been developed in parallel. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. (DOI: 10.1117/1.OE.52.5.053004) Subject terms: ray tracing; graphics processing unit-accelerated computing; optical simulation.
- Published
- 2013
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29. Genetic programming applied to automatic algorithm design in multi-scale inspection systems
- Author
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Wolfram Lyda, Tobias Haist, Wolfgang Osten, and Avinash Burla
- Subjects
Computer science ,business.industry ,Optical engineering ,Computer programming ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,General Engineering ,Evolutionary algorithm ,Genetic programming ,Image processing ,computer.software_genre ,Atomic and Molecular Physics, and Optics ,Automated X-ray inspection ,Software ,Algorithm design ,Computer vision ,Artificial intelligence ,Data mining ,business ,computer - Abstract
In recent years image-processing has become a central part of optical inspection and measurement systems. Typically, after measuring the given specimen by utilizing a suitable sensor, image-processing algorithms are used to detect dedicated features such as surface defects. These algorithms are usually designed, optimized, and tested by an image-processing expert according to the task specifications. A methodology (based on genetic programming) is presented to automatically generate, optimize, and test such algorithms without the necessity of an image-processing expert. We also present several examples of inspection tasks to support the concept. For efficiency, an automated multi-scale multi-sensor inspection strategy is employed.
- Published
- 2012
- Full Text
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30. Advantages of chromatic-confocal spectral interferometry in comparison to chromatic confocal microscopy
- Author
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David Fleischle, Wolfgang Osten, Florian Mauch, Wolfram Lyda, and Marc Gronle
- Subjects
business.industry ,Applied Mathematics ,Confocal ,Numerical aperture ,Interferometry ,Optics ,Robustness (computer science) ,Measuring principle ,Chirp ,Chromatic scale ,business ,Instrumentation ,Engineering (miscellaneous) ,Optical path length ,Mathematics - Abstract
Chromatic confocal microscopy (CCM) and spectral interferometry (SI) are established and robust sensor principles. CCM is a focus-based measurement principle, whose lateral and axial resolutions depend on the sensor's numerical aperture (NA), while the measurement range is given by the spectral bandwidth and the chromatic dispersion in the axial direction. Although CCM is a robust principle, its accuracy can be reduced by self-imaging effects or asymmetric illumination of the sensor pupil. Interferometric principles based on the evaluation of the optical path difference, e.g., SI, have proven to be robust against self-imaging. The disadvantage of SI is its measurement range, which is limited by the depth of focus. Hence, the usable NA and the lateral resolution are restricted. Chromatic-confocal spectral interferometry (CCSI) is a combination of SI and CCM, which overcomes these restrictions. The increase of robustness of CCSI compared to CCM due to the interferometric gain has been demonstrated before. In this contribution the advantages of CCSI in comparison to CCM concerning self-imaging artifacts will be demonstrated. Therefore, a new phase-evaluation algorithm with higher resolution concerning classical SI-based evaluation algorithms is presented. For the comparison of different sensor systems, a chirp comparison standard is used.
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- 2012
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31. Laterally chromatically dispersed, spectrally encoded interferometer
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Wolfram Lyda, Marc Gronle, Wolfgang Osten, and Florian Mauch
- Subjects
Focal point ,White light interferometry ,Materials science ,business.industry ,Materials Science (miscellaneous) ,Phase (waves) ,Physics::Optics ,Grating ,Interference (wave propagation) ,Signal ,Industrial and Manufacturing Engineering ,Wavelength ,Interferometry ,Optics ,Optoelectronics ,Business and International Management ,business - Abstract
We present a single-shot line sensor based on spectral interferometry. Light of a broadband laser source is chromatically dispersed by a grating and focused onto a line on the surface such that each focal point on this line is formed by another wavelength. The entire height profile is obtained by applying a phase evaluation algorithm to the registered interference signal, followed by a model-based approach. The sensor concept is finally verified by experimental results.
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- 2011
- Full Text
- View/download PDF
32. Fourier descriptors for defect indication in a multiscale and multisensor measurement system
- Author
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Tobias Haist, Wolfgang Osten, Avinash Burla, and Wolfram Lyda
- Subjects
Microlens ,Microscope ,Computer science ,business.industry ,Confocal ,Optical engineering ,System of measurement ,Fourier optics ,General Engineering ,Scale invariance ,Atomic and Molecular Physics, and Optics ,law.invention ,Lens (optics) ,symbols.namesake ,Fourier transform ,Optical microscope ,law ,Confocal microscopy ,symbols ,Computer vision ,Artificial intelligence ,business ,Shape analysis (digital geometry) - Abstract
Efficient inspection of an object for deformations and defects requires comparison with an existing real or simulated reference model. Fourier descriptor (FDs) based shape analysis is an effective method for describing a shape using the Fourier transform. This shape representation can be easily modified to achieve shift, rotation, and scale invariance. We propose two new methods, namely the ring sampling and the spiral sampling methods, which enable the usage of FDs in order to detect defects on micro-optical elements like microlens arrays. As an example the measurement data obtained from a confocal microscope has been used to show the effectiveness of the two approaches for both indicating and detecting surface defects. Microlens arrays with different types of defects including global (deformed lenses causing aberrations) and local defects (scratches) were simulated using a confocal microscopy simulation tool to test the reliability of the methods. A classifier differentiates between global and local defective lenses. In order to represent other kinds of objects using FDs, the methods can be easily modified or extended. The whole process has been implemented into an automated multiscale multisensor measurement system, which focuses on fast detection of defects on micro-optical and microelectromechanical systems.
- Published
- 2011
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33. Automated surface positioning for a non-null test interferometer
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Wolfram Lyda, Eugenio Garbusi, Goran Baer, and Wolfgang Osten
- Subjects
Surface (mathematics) ,Physics ,Null (radio) ,Plane (geometry) ,business.industry ,Optical engineering ,General Engineering ,Phase (waves) ,Test object ,Atomic and Molecular Physics, and Optics ,Interferometry ,Optics ,Astronomical interferometer ,business - Abstract
An automatic method for the positioning of the test surface in a non-null interferometer is presented. A major task in the interferometric testing of surfaces is to avoid the introduction of surface aberrations due to an incorrect placement of the test object in the interferometer cavity. In the case of plane and spherical surfaces, adjustment errors can usually be distinguished from surface figure errors and therefore removed, but in the case of aspherical surfaces this task becomes nontrivial. In this work, the effect on the measured phase due to lateral and axial displacements of the aspherical surface is calculated, and an adjustment method for the positioning of the surface at a predefined measurement location presented. Experimental results showing the feasibility of the proposed procedure are shown.
- Published
- 2010
- Full Text
- View/download PDF
34. Fourier descriptors for defect indication in a multiscale and multisensor measurement system.
- Author
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Avinash Burla, Tobias Haist, Wolfram Lyda, and Wolfgang Osten
- Subjects
SENSOR networks ,MEASUREMENT ,DEFORMATIONS (Mechanics) ,SIMULATION methods & models ,FOURIER transforms ,CONFOCAL microscopy ,OPTICAL aberrations ,MICROELECTROMECHANICAL systems - Abstract
Efficient inspection of an object for deformations and defects requires comparison with an existing real or simulated reference model. Fourier descriptor (FDs) based shape analysis is an effective method for describing a shape using the Fourier transform. This shape representation can be easily modified to achieve shift, rotation, and scale invariance. We propose two new methods, namely the ring sampling and the spiral sampling methods, which enable the usage of FDs in order to detect defects on micro-optical elements like microlens arrays. As an example the measurement data obtained from a confocal microscope has been used to show the effectiveness of the two approaches for both indicating and detecting surface defects. Microlens arrays with different types of defects including global (deformed lenses causing aberrations) and local defects (scratches) were simulated using a confocal microscopy simulation tool to test the reliability of the methods. A classifier differentiates between global and local defective lenses. In order to represent other kinds of objects using FDs, the methods can be easily modified or extended. The whole process has been implemented into an automated multiscale multisensor measurement system, which focuses on fast detection of defects on micro-optical and microelectromechanical systems. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
35. Automated surface positioning for a non-null test interferometer.
- Author
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Goran Baer, Eugenio Garbusi, Wolfram Lyda, and Wolfgang Osten
- Subjects
INTERFEROMETERS ,OPTICAL aberrations ,GEOMETRIC surfaces ,OPTICAL instruments ,OPTICS ,SPHERES ,IMAGING systems ,OPTOELECTRONIC devices - Abstract
An automatic method for the positioning of the test surface in a non-null interferometer is presented. A major task in the interferometric testing of surfaces is to avoid the introduction of surface aberrations due to an incorrect placement of the test object in the interferometer cavity. In the case of plane and spherical surfaces, adjustment errors can usually be distinguished from surface figure errors and therefore removed, but in the case of aspherical surfaces this task becomes nontrivial. In this work, the effect on the measured phase due to lateral and axial displacements of the aspherical surface is calculated, and an adjustment method for the positioning of the surface at a predefined measurement location presented. Experimental results showing the feasibility of the proposed procedure are shown. [ABSTRACT FROM AUTHOR]
- Published
- 2010
- Full Text
- View/download PDF
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