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Suche nach „[R.] [Stamp]“ hat 41 Publikationen gefunden
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    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenMaschinenbau und Mechatronik

    Beitrag (Sammelband oder Tagungsband)

    Florian Schneider, Roland Maurer, Christine Wünsche, R. Stamp, G. Smith

    Analysis of three different measurement strategies carried out with the TII-3D coordinate measurement system

    SPIE Optics + Photonics 2013, Optical Engineering + Applications

    2013

    DOI: 10.1117/12.2024001

    Abstract anzeigen

    Together with the group of interferometry based systems, coordinate measurement machines are an essential part of the metrology in the modern optical industry. Coordinate measurement machines commonly consist of a multi axes framework. They are designed to operate in a defined three dimensional work zone, where every possible point can be reached by the measurement tool tip. This basic design principle leads to some interdependent challenges. A detailed measurement result needs a large amount of measurement points to detect even minor irregularities and short-wave errors. However, a rising of the amount of measurement points increases the corresponding measurement time analogous. On the other hand, the extended operation time increases the access of undesired thermal and dynamic influences, which cause multiple errors to the measurement result. Furthermore, modern production processes need rapid metrology systems to aid the machining time. This paper discusses results obtained by operating with three different measurements in order to find an agreement between speed and certainty of the coordinate measurement machine. The topographic coordinate measurement system TII- 3D had been re-developed at the University of Applied Sciences Deggendorf in the laboratory of optical Engineering and it is equipped with three different measurement strategies. The first mode, the Track-Mode operates in concentric circles on top of the surface of the object to be measured. The Spiral-Mode measures along a dynamic moveable spiral line and the Section-Mode produces multiple cross-sections. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Beitrag (Sammelband oder Tagungsband)

    Florian Schneider, Markus Schinhärl, Christian Vogt, Roland Maurer, Peter Sperber, Rolf Rascher, R. Stamp, G. Smith

    Effects of mechanical inaccuracies on the measurement result in metrology systems

    Proceedings of the 5th International Symposium on Advanced Optical Manufacturing and Testing Technologies: Optical Test and Measurement Technology and Equipment, vol. 7656

    2010

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Vortrag

    Christian Vogt, R. Stamp, G. Smith, Rolf Rascher, Peter Sperber, Florian Schneider, Roland Maurer, Markus Schinhärl

    Strategies for grinding optical free-forms using ball-shaped grinding wheels

    SPIE Optifab, Rochester, NY, USA

    2009

    Abstract anzeigen

    The demand for non-spherical surfaces and free-forms is steadily growing. Aspherical lenses can reduce the number of necessary lenses in optical systems e.g. used for lithographic devices for production of microprocessors. Parabolic mirrors can be used to focus light beams highly efficiently because of low absorption rates without colour distortion. Combined optical devices with included mechanical functions for assembly reduce necessary production steps. The most common pre-machining method for small numbers of high-precision lenses and mirrors is grinding. Depending on the required shape there are different options for generating surfaces e. g. spheres, parabolic mirrors or combined forms. The most flexible ones are grinding with (i) workpiece and ball-shaped tool rotating and (ii) fixed workpiece with ball-shaped tool rotating. In this manuscript grinding strategies dealing with meander and spiral tool paths are investigated in order to define which strategy works best for machining off-axis parabolic mirrors.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Markus Schinhärl, R. Stamp, Elmar Pitschke, Rolf Rascher, L. Smith, G. Smith, Andreas Geiss, Peter Sperber

    Advanced techniques for computer-controlled polishing

    Current Developments in Lens Design and Optical Engineering IX, vol. 7060, no. 70600Q ff.

    2008

    DOI: 10.1117/12.808036

    Abstract anzeigen

    Computer-controlled polishing has introduced determinism into the finishing of high-quality surfaces, for example those used as optical interfaces. Computer-controlled polishing may overcome many of the disadvantages of traditional polishing techniques. The polishing procedure is computed in terms of the surface error-profile and the material removal characteristic of the polishing tool, the influence function. Determinism and predictability not only enable more economical manufacture but also facilitate considerably increased processing accuracy. However, there are several disadvantages that serve to limit the capabilities of computer-controlled polishing, many of these are considered to be issues associated with determination of the influence function. Magnetorheological finishing has been investigated and various new techniques and approaches that dramatically enhance the potential as well as the economics of computer-controlled polishing have been developed and verified experimentally. Recent developments and advancements in computer-controlled polishing are discussed. The generic results of this research may be used in a wide variety of alternative applications in which controlled material removal is employed to achieve a desired surface specification, ranging from surface treatment processes in technical disciplines, to manipulation of biological surface textures in medical technologies.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Beitrag (Sammelband oder Tagungsband)

    Markus Schinhärl, Christian Vogt, Andreas Geiss, R. Stamp, Peter Sperber, L. Smith, G. Smith, Rolf Rascher

    Forces acting between polishing tool and workpiece surface in magnetorheological finishing

    Proceedings of SPIE, Volume 7060, Current Developments in Lens Design and Optical Engineering IX (Optical Engineering + Applications, San Diego, CA, USA; August 10-14, 2008)

    2008

    DOI: 10.1117/12.794196

    Abstract anzeigen

    Magnetorheological finishing is a computer-controlled polishing technique that is used mainly in the field of high-quality optical lens production. The process is based on the use of a magnetorheological polishing fluid that is able, in a reversible manner, to change its viscosity from a liquid state to a solid state under the control of a magnetic field. This outstanding characteristic facilitates rapid control (in milliseconds) of the yield stress, and thus the pressure applied to the workpiece surface to be polished. A three-axis dynamometer was used to measure the forces acting between the magnetorheological fluid and the workpiece surface during determination of the material removal characteristic of the polishing tool (influence function). The results of a testing series using a QED Q22-X MRF polishing machine with a 50 mm wheel assembly show that the normal forces range from about 2 to 20 N. Knowledge of the forces is essential, especially when thin workpieces are to be polished and distortion becomes significant. This paper discusses, and gives examples of, the variation in the parameters experienced during a programme of experiments, and provides examples of the value of this work.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Markus Schinhärl, Rolf Rascher, R. Stamp, L. Smith, G. Smith, Peter Sperber, Elmar Pitschke

    Utilisation of time-variant influence functions in the computer-controlled polishing

    Precision Engineering, vol. 32, no. 1, pp. 47-54

    2008

    DOI: 10.1016/j.precisioneng.2007.04.005

    Abstract anzeigen

    In the computer controlled polishing, a polishing tool moves in a well-defined manner across the workpiece surface in order to individually remove the surface error-profile. The commonly used technique to calculate the moving of the polishing tool is the dwell time method. Based on a constant (time-invariant) removal characteristic of the polishing tool (influence function) the amount of material to be removed is controlled via the dwell time. The longer the polishing tool is in contact with a particular area of the workpiece, the more material is removed at this position. Mathematical basics to calculate dwell time-profiles are shown, and a new approach considering time-variant influence functions for the computer controlled polishing is introduced. The results point out that time-variant influence functions may contribute to further decrease the process time, and thus to make a computer controlled polishing process more efficient. The reduction of the process time was observed to approximately 35% using a combination of the dwell time method with time-variant influence functions.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Elmar Pitschke, Markus Schinhärl, Rolf Rascher, Peter Sperber, L. Smith, R. Stamp, M. Smith

    Simulation of a complex optical polishing process using a neural network

    Robotics and Computer-Integrated Manufacturing, vol. 24, no. 1, pp. 32-37

    2008

    DOI: 10.1016/j.rcim.2006.07.003

    Abstract anzeigen

    Most modern manufacturing processes change their set of parameters during machining in order to work at the optimum state. But in some cases, like computer-controlled polishing, it is not possible to change these parameters during the machining. Then usually a standard set of parameters is chosen which is not adjusted to the specific conditions. To gather the optimum set of parameters anyway simulation of the process prior to manufacturing is a possibility. This research illustrates the successful implementation of a neural network to accomplish such a simulation. The characteristic of this neural network is described along with the decision of the used inputs and outputs. Results are shown and the further usage of the neural network within an automation framework is discussed. The ability to simulate these advanced manufacturing processes is an important contribution to extend automation further and thus increase cost effectiveness.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Markus Schinhärl, G. Smith, R. Stamp, Rolf Rascher, L. Smith, Elmar Pitschke, Peter Sperber, Andreas Geiss

    Mathematical modelling of influence functions in computer-controlled polishing. Part II

    Applied Mathematical Modelling, vol. 32, no. 12, pp. 2907-2924

    2008

    Abstract anzeigen

    Computer-controlled polishing (CCP) is commonly used to finish high-quality surfaces, such as optical lenses. Based on magnetorheological finishing (MRF), a mathematical model to calculate the polishing tool characteristic (influence function) was developed and verified experimentally. The second part of this paper describes the calculation of the distribution of material removal within the size of an influence function and is based on Preston’s fundamental polishing equation. The complete influence function model was implemented using MATLAB. The result is a user-friendly and easy-to-use software tool that enables fast computation of MRF influence functions without the current cumbersome determination procedure, and thus gives improved and more economical production of high-quality surfaces.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Markus Schinhärl, G. Smith, R. Stamp, Rolf Rascher, L. Smith, Elmar Pitschke, Peter Sperber, Andreas Geiss

    Mathematical modelling of influence functions in computer-controlled polishing. Part I

    Applied Mathematical Modelling, vol. 32, no. 12, pp. 2888-2906

    2008

    Abstract anzeigen

    Computer-controlled polishing (CCP) is commonly used to finish high-quality surfaces, such as optical lenses. Based on magnetorheological finishing (MRF), a mathematical model to calculate the polishing tool characteristic (influence function) was developed and verified experimentally. The first part of this paper introduces the model to predict the size and shape of an influence function. The second part of this paper describes the calculation of the distribution of material removal within the size of an influence function. The model supersedes the current cumbersome procedure for determining an influence function and thus results in considerably improved and more economical manufacture. Furthermore, the model enables the quality of the final surface to be enhanced when polishing complex, for example aspherical or free-form, workpiece geometries and provides the first step in the application of time-variant influence functions.

    Elektrotechnik und MedientechnikIQMAMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Werner Frammelsberger, Günther Benstetter, J. Kiely, R. Stamp

    C-AFM-based thickness determination of thin and ultra-thin SiO2 films by use of different conductive-coated probe tips

    Applied Surface Science, vol. 253, no. 7, pp. 3615-3626

    2007

    Abstract anzeigen

    The influence of the probe tip type on the electrical oxide thickness result was researched for four differently coated conductive tip types using SiO2 (oxide) films with optical thickness of 1.7–8.3 nm. For this purpose, conductive atomic force microscopy (C-AFM) was used to measure more than 7200 current–voltage (IV) curves. The electrical oxide thickness was determined on a statistical basis from the IV-curves using a recently published tunnelling model for C-AFM application. The model includes parameters associated with the probe tip types used. The evolution of the tip parameters is described in detail. For the theoretical tip parameters, measured and calculated IV-curves showed excellent agreement and the electrical oxide thickness versus the optical oxide thickness showed congruent behaviour, independent of the tip type. However, differences in the electrical oxide thickness were observed for the different tip types. The theoretical parameters were modified experimentally in order to reduce these differences. Theoretical and experimental tip parameters were compared and their effect on the differences in the electrical oxide thickness is discussed for the different tip types. Overall, it is shown that the proposed model provides a comprehensive framework for determining the electrical oxide thickness using C-AFM, for a wide range of oxide thicknesses and for differently coated conductive tips.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Markus Schinhärl, G. Smith, Andreas Geiss, L. Smith, Rolf Rascher, Peter Sperber, Elmar Pitschke, R. Stamp

    Calculation of MRF influence functions

    Optical Manufacturing and Testing VII, vol. 6671

    2007

    Abstract anzeigen

    Magnetorheological finishing (MRF) is a commonly used computer-controlled polishing (CCP) technique for high precision optical surfaces. The process is based on a magnetorheological abrasive fluid, which stiffens in a magnetic field and may be employed as a sub-aperture polishing tool. Dependent upon the surface error-profile of the workpiece and the polishing tool characteristic (influence function) an individual polishing procedure is calculated prior to processing. However, determination of the influence function remains a time consuming and laborious task. A user friendly and easy to use software tool has been developed, which enables rapid computation of MRF influence functions dependent on the MRF specific parameters, such as, magnetic field strength or fluid viscosity. The software supersedes the current cumbersome and time consuming determination procedure and thus results in considerably improved and more economical manufacture. In comparison with the conventional time period of typically 20 minutes to ascertain an influence function, it may now be calculated in a few seconds. An average quality improvement of 57% relating to the peak-valley (PV) value, and approximately 66% relating to the root-mean-square (RMS) of the surface error-profiles was observed during employment of the artificial computed influence functions for polishing.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Elmar Pitschke, Peter Sperber, Rolf Rascher, R. Stamp, M. Smith, L. Smith, Markus Schinhärl

    Lens production enhancement by adoption of artificial influence functions and a knowledge-based system in a magnetorheological finishing process

    Optical Manufacturing and Testing VII, vol. 6671, no. September

    2007

    DOI: 10.1117/12.761356

    Abstract anzeigen

    High quality optical lenses are usually finished by magnetorheological finishing (MRF). In this process an abrasive fluid, with the ability to stiffen in a magnetic field, is used as the polishing tool in a computer-controlled machine tool. Although the machine is automated it is necessary for a skilled operator to set the machine and make judgments with regard to its operation. An investigation has been under way to examine the detailed operation of the MRF process, and the information that is necessary to establish best practice. This has resulted in the incorporation of a knowledge based system (KBS) into the machine control regime, and a methodology for the creation of artificial polishing tool characteristics, the machine influence function. The incorporation of the these elements has been instrumental in the operation of an enhanced MRF machine. This has been subject to extensive test procedures, and it has been demonstrated that the production process may be enhanced significantly and consistently. Batch production time may be significantly reduced, a figure in excess of a 50% reduction was met consistently during prolonged operation. Furthermore the incorporation of the KBS is instrumental in increasing the automation of the MRF process, reducing the levels of manual input necessary to manage machine operation.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Markus Schinhärl, Rolf Rascher, R. Stamp, G. Smith, L. Smith, Elmar Pitschke, Peter Sperber

    Filter algorithm for influence functions in the computer-controlled polishing of high-quality optical lenses

    International Journal of Machine Tools and Manufacture, vol. 47, no. 1, pp. 107-111

    2007

    Abstract anzeigen

    Computer controlled polishing (CCP) is widely used in the production of high-quality optical lenses. CCP enables surface error-profile-dependent calculation of polishing sequences prior to processing, and facilitates the cost-effective manufacture of high-quality optical surfaces. Calculation of an individual polishing sequence requires knowledge of the surface error-profile in addition to knowledge of the material removal characteristic (influence function) of the polishing tool. Measurement errors during both determination of the surface error-profile, and the influence function, may lead to an incorrect polishing sequence calculation, which in turn may result in an inadequate product quality. A new method has been developed which minimises the effects of measurement errors on the influence function. The resulting algorithm renders an influence function symmetrical and filters noisy data. Practical polishing tests with magnetorheological finishing have been performed to verify this new technique. The improvement of the peak-valley (PV) value of the surfaces polished with the symmetrical rendered influence function was observed to average 14% greater than that which related to the PV value improvement of those surfaces which were polished with the unmodified influence function. The algorithm developed is based on software and is easily implemented. Thus, artificial enhancement of an influence function is a straightforward technique to improve the result of the polishing process.

    Elektrotechnik und MedientechnikIQMAMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Werner Frammelsberger, Günther Benstetter, J. Kiely, R. Stamp

    Thickness determination of thin and ultra-thin SiO2 films by C-AFM IV-spectroscopy

    Applied Surface Science, vol. 252, no. 6, pp. 2375-2388

    2006

    Abstract anzeigen

    Conductive atomic force microscopy was used to determine the electrical oxide thickness for five different silicon dioxide layers with thickness in the order of 1.6–5.04 nm. The electrical thickness results were compared with values determined by ellipsometry. A semi-analytical tunnelling current model with one single parameter set was used to superpose current/voltage curves in both the direct tunnelling and the Fowler–Nordheim tunnelling regime regions. The overall electrical oxide thickness was determined by statistical means from results of nearly 3000 IV-curves recorded for different conductive CoCr-coated tips. Good agreement between the shape of model and experimental data was achieved, widely independent of the oxide thickness. Compared with the ellipsometry value, the electrical thickness was larger by a value of 0.36 nm (22%) for the thinnest oxide and smaller by a value of 0.31 nm (6%) for the thickest oxide, while intermediate values yielded differences better than 0.15 nm (<<6%). The physical differences between the measurement techniques were shown to contribute to this observation. In addition, statistical deviations between single and multiple measurements using a single tip and using a number of different tips were analysed. The causes, for example, natural oxide thickness variations, tip wear, air humidity induced effects and contaminations, are evaluated and discussed. The method proposed was able to determine the electrical oxide thickness with a standard deviation in the order of ±±6–9%. The results suggest that for optimal results it is necessary to perform several repetitions of IV-measurements for one sample and, in addition, to employ more than one tip.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Vortrag

    Markus Schinhärl, Andreas Geiss, Rolf Rascher, Peter Sperber, R. Stamp, L. Smith, G. Smith, Elmar Pitschke

    Coherences between influence function size, polishing quality and process time in the magnetorheological finishing

    Current Developments in Lens Design and Optical Engineering VII, San Diego, CA, USA

    2006

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Elmar Pitschke, Markus Schinhärl, Rolf Rascher, Peter Sperber, L. Smith, R. Stamp, M. Smith

    Simulation of a complex optical polishing process using a neural network

    Robotics and Computer-Integrated Manufacturing, vol. 24, no. 1, pp. 32-37

    2006

    DOI: 10.1016/j.rcim.2006.07.003

    Abstract anzeigen

    Most modern manufacturing processes change their set of parameters during machining in order to work at the optimum state. But in some cases, like computer-controlled polishing, it is not possible to change these parameters during the machining. Then usually a standard set of parameters is chosen which is not adjusted to the specific conditions. To gather the optimum set of parameters anyway simulation of the process prior to manufacturing is a possibility. This research illustrates the successful implementation of a neural network to accomplish such a simulation. The characteristic of this neural network is described along with the decision of the used inputs and outputs. Results are shown and the further usage of the neural network within an automation framework is discussed. The ability to simulate these advanced manufacturing processes is an important contribution to extend automation further and thus increase cost effectiveness.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Markus Schinhärl, Andreas Geiss, Rolf Rascher, Peter Sperber, R. Stamp, L. Smith, G. Smith, Elmar Pitschke

    Coherences between influence function size, polishing quality and process time in the magnetorheological finishing

    Current Developments in Lens Design and Optical Engineering VII, vol. 6288

    2006

    DOI: 10.1117/12.678720

    Abstract anzeigen

    Magnetorheological finishing (MRF) is a computer controlled polishing process (CCP), which is commonly used in the field of high quality optical lens production. The process uses the material removal characteristic of the polishing tool (influence function) and the surface error-profile to calculate individual, surface error-profile dependent polishing sequences. At the University of Applied Sciences Deggendorf a testing series with a magnetorheological finishing machine has been performed, and effects of the influence function size and its removal capacity on the polishing quality and the process time have been investigated. The result of the research shows that the influence function size has a major effect on the process time, whereas the polishing quality is nearly independent of the influence function size. During the testing series the process time was significantly reduced using an appropriate influence function size. The process time decreased about 9% relating to the original influence function.

    Angewandte Naturwissenschaften und WirtschaftsingenieurwesenElektrotechnik und MedientechnikHochschulleitung und -einrichtungenMaschinenbau und Mechatronik

    Zeitschriftenartikel

    Elmar Pitschke, Markus Schinhärl, Peter Sperber, Rolf Rascher, R. Stamp, M. Smith, L. Smith

    Correlation between influence- function quality and predictability of a computer-controlled polishing process

    Optical Engineering, vol. 45, no. 6

    2006

    DOI: 10.1117/1.2213630

    Abstract anzeigen

    A mathematical method has been developed to analyze influence functions that are used in a computer-controlled polishing process. The influence function itself is usually generated by some kind of calibration where the exact procedure is dependent on the process used. The method is able to determine asymmetries in an influence function. Application of this method yields a value that may be used to judge the quality of an influence function. That quality is also an indicator of the variance of the evolving surface error profile, since a close relationship between it and the polishing process exists. On the basis of an ideal, theoretical process, a model to handle and quantify the result of a real polishing process is described. Practical application of this model demonstrates the effect of influence-function quality on the polishing result. Based on this model, the predictability of the polishing result is evaluated. This initiative to judge influence functions by their quality is an important contribution to the development of computer-controlled polishing. Due to improved process reliability, the reject rate will decrease, and the result will be more economic manufacture.