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Suche nach „[Fütterer] [Gerald]“ hat 50 Publikationen gefunden
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    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer, Simon Wittl, Lucas Bauer, Michael Wagner

    Alignment and thermal drift aspects of a four-tilted-mirror student project telescope

    Proceedings of SPIE 11171 (Sixth European Seminar on Precision Optics Manufacturing, 1117101 [April 9th-10th 2019, Teisnach]), Bellingham, WA, USA

    2019

    DOI: 10.1117/12.2530076

    Abstract anzeigen

    The Deggendorf Institute of Technology (DIT) and its Faculty of Applied Natural Sciences and Industrial engineering transfer a broad spectrum of knowledge to the students. The clarification of the interrelations that exist between seemingly isolated fields of knowledge is a permanent process. In order to put this into practice, a telescope construction project was started. The base of the in-house student project is the Technology Campus in Teisnach, which bundles capacities for process development, production and measurement of high-precision optics, including telescope optics. A first optical design, which is based on a subset of the parameter space published in 1989 by M. Brunn1, 2 (later built by D. Stevick as f/12-system3 ), made use of a primary mirror M1 with a diameter of 400 mm. An f/8-system provide a Strehl ratio SR ≥ 0.8 over an entire field of view of 0.7° deg. Even if this seems to be sufficient, manufacturing tolerances, adjustment tolerances, thermal drift and positional changes considerably reduce the Strehl ratio. In order to obtain reliable values of acceptable tolerances, statistical Monte Carlo analyses had been carried out. As consequences, the tube design was changed and the design of new mirror mounts started. This was done to achieve the required stiffness. The new tube designs, one based on carbon-fiber-reinforced polymer (CFRP) and one based on FeNi36, had been tested by using FEM analysis. In addition, the practicability of deep learning based aberration detection was tested. Zernike polynomials obtained by analyzing the star images with a Convolutional Neuronal Network (CNN). The current state of the development is described.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer

    Wave front sensing for metrology by using optical filter

    Proceedings of SPIE 11171 (Sixth European Seminar on Precision Optics Manufacturing, 1117101 [April 9th-10th 2019, Teisnach]), Bellingham, WA, USA

    2019

    DOI: 10.1117/12.2530013

    Abstract anzeigen

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

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer, W. Krais, A. Engelbrecht, A. Sperl, S. Killinger, M. Werni

    Abschattungsfreies Multi-Schiefspiegel-Teleskop als studentisches Entwicklungsprojekt

    DGaO Proceedings zur 119. Jahrestagung in Aalen (22.-26.05.2018) 2018

    2018

    Abstract anzeigen

    An der Fakultät für Angewandte Naturwissenschaften und Wirtschaftsingenieurwesen der Technische Hochschule Deggendorf wird ein breites Wissensspektrum vermittelt. Um dieses praxisnah zu gestalten, wurde ein Teleskopbau-Projekt ins Leben gerufen. Mit dem Technologie-Campus Teisnach existiert die Basis für die Fertigung und Messung hoch präziser Teleskop-Optiken. Ausgangsparameter sind 400 mm Durchmesser des Primärspiegels und der Ansatz, am Markt bestehende Systeme in der optischen Abbildungsleistung einzuholen. Das optische Design beruht auf einer Untermenge des Parameterraums, der 1989 von M. Brunn veröffentlicht wurde. Das Konzept wurde später von D. Stevick als F12 System (mit Bezug auf die Arbeit von M. Paul, 1935) gebaut. Das THD-Projekt startete mit einem Vergleich von F7 Systemen, die in Zemax implementiert wurden. Die Abbildungsleistung wurde über ein Feld von 0,7 ° deg verglichen. Das mechanische Design schließt FEM Simulation thermischer Effekte an leichtgewichteten Spiegeln ein. Unterschiedliche Tuben wurden miteinander verglichen, einschließlich CFK Monocoquetubus. Ein weiterer Punkt ist die Auslegung der Nachführung. Es wird der Stand der Entwicklung dargelegt.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer, W. Krais, A. Engelbrecht, A. Sperl, S. Killinger, M. Werni

    Developing a four-tilted-mirror telescope as a student project

    Optics Education and Outreach V, vol. volume 10741

    2018

    ISBN: 9781510620537

    DOI: 10.1117/12.2320542

    Abstract anzeigen

    The Faculty of Applied Natural Sciences and Industrial engineering, which is a part of the Deggendorf Institute of Technology (DIT), transfers a broad spectrum of knowledge to the students. Edifying the interrelations, which are present between seemingly isolated fields of knowledge, is a permanent process. In order to make this practical, a telescope construction project was launched. The Technology Campus Teisnach bundles capacities for process development, production and measurement of highprecision optics. This also includes telescope optics. This qualifies the Campus for being the base of the in-house project. Fixed boundary conditions are e.g. 400 mm diameter of the primary mirror M1 and the objective to realize an image performance, which is equivalent to commercial telescopes. Furthermore, an unobscured tilted-mirror-system should be realized. The optical design, which was chosen as a result of an analysis of the state of the art, is based on a subset of the parameter space, which was published in 1989 by M. Brunn 1, 2. The concept was later built by D. Stevick as f/12-system (with reference to the work of M. Paul, 1935) 3. The DIT project started with a comparison of f/7-systems. They had been implemented in the optical design software Zemax. The imaging performance was compared within a field of view of 0.7 ° deg. The mechanical design includes FEM simulation of thermal effects on slightly weighted mirrors. Different tubes had been compared, including carbonfiber- reinforced-polymer (CFRP) Monocoquetubus. Another task is the realization of fast and precise tracking. The state of the development is set out.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer

    CSLM illumination for 1D and 2D encoded holographic 3D displays

    Illumination Optics V; SPIE Illumination Optics Conference; SPIE Optical Systems Design (OSD) [May 14-16, 2018; Frankfurt, Germany], vol. 10693

    2018

    ISBN: 9781510619234

    DOI: 10.1117/12.2312745

    Abstract anzeigen

    To leave the path of classic holography and limit the space-bandwidth-product of the holographic reconstruction is one way to enable interactive real time holographic 3D displays. Thus, a couple of major problems - among several others - can be reduced to a practical level. This holds e.g. for the computation power, the data transfer rate and the pixel count of the spatial light modulator (SLM) used. Although this idea is almost twenty years old, the maximum time span of IP protection, displays based on space-bandwidth-limited CGH reconstruction, which also can be referred to as spacebandwidth- limited reconstruction of wave front segments, are still not on the market. There are several technological reasons for that. However, the technological barriers can be tackled gradually. One problem to be solved is the illumination of the entrance plane of the preferable complex valued spatial light modulator (CSLM). Here, CSLM means to modulate the phase and the amplitude of each pixel. The display diagonals of desktop and TV type CSLM might be e.g. 32 and 65 inch respectively. In other words, reasonable large collimated illumination wave fields are mandatory. In addition a small form factor is a must have in order to obtain commercial success. The solution is an optical system design, which is based on Bragg diffraction based volume gratings. Classic refractive optics fails here. In other words, Bragg diffraction based volume gratings are key components of illumination units of holographic 3D displays. They can be used within a parameter space, which cannot be addressed by surface relief type diffraction optics. But their layout depends on the parameters of the illumination wave field, which has to be tailored in regards to the optical system of the discrete, e.g. 1D or 2D encoded holographic 3D display. This will be described in more detail. The example used for the description is a double wedge type backlight unit. Furthermore, it will be explained why the use of complex valued secondary light sources is a must have in holographic 3D displays. For this, a short explanation of coherent retinal inter object point cross talk will be given too. Finally, the description of the wave field shaping (WFS), which is required in order to form the optimized complex valued light source planes, is provided. In other words, a description of a tailored coherence preparation is given, which is up to now not state of the art. The cause and effect relationship of the light propagating from the primary light sources, which are lasers, to the final receptor, which is the retina, will be pointed out. Although this tailored partial coherent illumination totally differs from the state of the art of information displays, it might help to understand a technology, which will come in the next decades.

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer

    Optimization of the complex coherence function for diffraction-based wavefront transformations

    Unconventional Optical Imaging

    2018

    ISBN: 9781510618800

    DOI: 10.1117/12.2307245

    Abstract anzeigen

    Partial coherence is used in a plurality of applications, magnifying microscopic imaging, interferometric measurement, lithographic imaging, CGH based wave front shaping, interference lithography and space-bandwidth-limited wave front reconstruction, just to name a few. In some applications the primary light source is characterized by a limited coherence length and an extended angular spectrum of plane waves, which has to be narrowed, e.g. if an Excimer laser is used. Sometimes the angular spectrum of plane waves of the primary light source has to be increased in order to be practical. There are several possibilities in general, the primary light source can be used directly, the system has to be adapted or the coherence function Γ has to be tailored in order to provide the specific requirements. Almost all embodiments come with little changes of the light sources coherence properties only. For example, to use a spectral bandpass filter or to limit the size of the light source seem to be the standard solution for almost everything. However, more advanced tailoring of the complex valued coherence function Γ leads to an increased image quality, e.g. in interferometers, but is not limited to this, reduces background noise, decouples Fizeau cavities or it enables complete new illumination and imaging system designs, which provide unique features. This aspect will be discussed herein. Furthermore, the propagation of the complex coherence will be taken into account. This is done in order to provide defined conditions in defined planes of imaging devices. In other words, the usage of the Wiener-Khintchin theorem and the van Cittert-Zernike theorem is just a part of the system analysis and system optimization, which has to be done. Although generic approaches are used, discrete light source layouts are strongly related to the discrete optical devices, which make use of them. The specific tailoring of the complex coherence function, which is related to the space-bandwidth-limited reconstruction of wave front segments, which also can be referred to as space-bandwidth-limited CGH reconstruction, will be described in more detail. For this type of real time dynamic imaging two major problems - among several others - have to be solved. One problem is the huge computation power and the other one is the coherent retinal cross talk of adjacent image points, which are reconstructed in the image volume. The disclosed layouts of tailored secondary light sources are based on the Wiener-Khintchin theorem and the van Cittert-Zernike theorem. Both problems, which are mentioned above, can be solved. Tailored complex valued light sources reduce the required computation power by enabling reduced coherent overlay of sub-CGH areas. Furthermore, they reduce the coherent retinal cross talk of dynamic real time spacebandwidth- limited CGH reconstruction, which is used in advanced imaging applications, too. This results in an increased image quality of partial coherent wave field reconstruction based imaging.

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    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer, Rolf Rascher, C. Pruß, H. Harsch, W. Osten, Alexander Haberl, Johannes Liebl

    Model based error separation of power spectral density artefacts in wavefront measurement

    Proceedings of SPIE 10749 (SPIE Optical Engineering + Applications Conference on Interferometry XIX [August 19-23, 2018; San Diego, CA, USA])

    2018

    DOI: 10.1117/12.2321106

    NachhaltigAngewandte Naturwissenschaften und WirtschaftsingenieurwesenIPH Teisnach

    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer, Alexander Haberl, Johannes Liebl

    Contribution of the phase transfer function of extended measurement cavities to mid spatial frequencies and the overall error budget

    Proceedings of SPIE 10829 (Fifth European Seminar on Precision Optics Manufacturing [April 10-11, 2018; Teisnach])

    2018

    ISBN: 978-1-5106-2270-8

    DOI: 10.1117/12.2318711

    Abstract anzeigen

    A challenge of coaxial - measurement cavity based - interferometer is to realize an interference contrast in the vicinity of one and to realize a complete elimination of the parasitic reflections. Another challenge, which also exists in non-coaxial setups, is the phase transfer function of extended measurement cavities. Ideally, the surface under test (SUT) and the reference surface (REF) are both exactly imaged onto the detector plane. In practice, SUT and REF have to be placed within the depth of field (DOF), which refers to the object space. The term depth of focus refers to the image space. To avoid confusion, the depth of field might be referred to as DOOF (depth of object field) and the depth of focus might be referred to as DOIF (depth of image field). However, in many measurement situations, the REF is not placed within the DOOF, which is the small z-range, which is imaged onto the detector plane. Furthermore, the phase transfer function (PTF) of the REF and the image distortion of the REF are both dependent on the focal plane used to image the SUT onto the detector plane. Effects as phase deformation, image distortion and image blurring have to be taken into account when using extended measurement cavities. This can be done by using a look up table (LUT), which contains simulated and/or calibrated data. Thus, the related system error can be subtracted. A remaining challenge is an unknown object under test (OUT), which is measured by using a double path arrangement. The measured wave front depends on the two surfaces of the OUT and the position of the return mirror. For simplicity, a homogeneous substrate and a perfect return mirror might be presumed. The simulation of waves propagating within extended measurement cavities, as well as measurement results, will be discussed. In addition, the influence on the power spectral density (PSD) will be described. This is important for high end correction techniques as e.g. magneto rheological figuring (MRF) and ion beam figuring (IBF).

    NachhaltigAngewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer

    Advantages of on-axis PBS based Fizeau interferometers

    DGaO Proceedings zur 118. Jahrestagung in Dresden (06.-10.06.2017)

    2017

    NachhaltigAngewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer

    Fast Fizeau interferometer with polarization selective reference and reduced measurement uncertainty for production integrated measurement

    Forschungsbericht 2016/2017 der Technischen Hochschule Deggendorf

    2017

    DigitalAngewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Patent

    Gerald Fütterer

    A Display for Two-Dimensional and/or Three-Dimensional Images

    2017

    NachhaltigAngewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer

    Tailored complex degree of mutual coherence for plane-of-interest interferometry with reduced measurement uncertainty

    Proceedings of SPIE 10448 (SPIE Optifab [October 16-19, 2017; Rochester, NY, USA])

    2017

    DOI: 10.1117/12.2279834

    Abstract anzeigen

    A problem of interferometers is the elimination of parasitic reflections. Parasitic reflections and modulated intensity signals, which are not related to the reference surface (REF) or the surface under test (SUT) in a direct way, can increase the measurement uncertainty significantly. In some situations standard methods might be used in order to eliminate reflections from the backside of the optical element under test. For instance, match the test object to an absorber, while taking the complex refractive index into account, can cancel out back reflections completely. This causes additional setup time and chemical contamination. In some situations an angular offset might be combined with an aperture stop. This reduces spatial resolution and it does not work if the disturbing wave field propagates in the same direction as the wave field, which propagates from the SUT. However, a stack of surfaces is a problem. An increased spectral bandwidth might be used in order to obtain a separation of the plane-of-interest from other planes. Depending on the interferometer used, this might require an optical path difference of zero or it might cause a reduction of the visibility to V < 0.5. Contrary to these methods, a tailored complex degree of mutual coherence can be used. High visibility is obtained for a single plane-of-interest. Wave fields of interest are shifted against each other. The reduction of the measurement uncertainty, as well as the embodiment of a modified interferometer, will be discussed.

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    Beitrag (Sammelband oder Tagungsband)

    Gerald Fütterer

    Polarization-Fizeau interferometer enabling phase measurement with reduced uncertainty

    Proceedings of SPIE 10326 (Fourth European Seminar on Precision Optics Manufacturing, 1032601 [April 4th-5th 2017, Teisnach])

    2017

    DOI: 10.1117/12.2272001

    NachhaltigAngewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Zeitschriftenartikel

    Gerald Fütterer

    Enabling Holographic 3D Displays with Bragg Diffraction Based Volume Gratings and First Approaches to the Reduction of Diffractive Cross Talk

    Bavarian Journal of Applied Sciences, no. 2, pp. 130-145

    2016

    DOI: 10.25929/276j-2q41

    Abstract anzeigen

    Photonics products often require enhanced optical functionality, which cannot be provided by state of the art optics. This is the case when high-end optical systems as for example holographic 3D displays are developed. Implementation of Bragg diffraction based volume gratings enables small form factor and high definition (HD) natural viewing experience of 3D objects. This is important for modeling 3D data, prototyping, CAD-CAM, computer-integrated manufacturing (CIM), global 3D teleconferencing and mobile infotainment. For example, holographic 3D displays, which are based on space bandwidth limited wave segment reconstruction, profit from the specific characteristics of thick hologram gratings, which can be referred to as Bragg diffraction based volume gratings. It is explained how to adapt angular, spectral and polarization selectivity in order to provide specific optical functionality, which is mandatory in order to realize HD holographic 3D displays. A short introduction to backlight units (BLU), complex valued spatial light modulators (C-SLM) and combined field lenses (cFL) of holographic 3D displays is given. The description of Bragg diffraction based volume gratings is based on the coupled wave theory (CWT). The usage of the 2nd on-Bragg maximum modulation is described. The advantage of the 2nd Bragg diffraction order is explained. Polarization beam splitter (PBS) geometries are described. Specific layouts of holographic 3D displays are explained. BLU and cFL are evaluated. It is shown how the suppression of diffractive crosstalk can be obtained. Oftmals benötigen neue Produkte der Photonik eine erweiterte optische Funktionalität, die nicht von optischen Standard-Komponenten bereitgestellt werden kann. Dies ist auch für die Entwicklung von holographischen 3D-Displays der Fall. Hierbei ermöglicht die Implementierung von Volumengittern, die auf der Bragg-Beugung basieren, eine kompakte Bauweise und eine natürliche Wahrnehmung von 3D-Objekten in HD-Auflösung. Dies ist für die Modellierung von 3D-Daten, die Erstellung von Prototypen, CAD-CAM, Computer integrierte Fertigung (CIM), weltweit arbeitende Telekonferenz-Systeme und mobiles Infotainment von Bedeutung. Holographische 3D-Displays, die auf einer, in der Bandbreite limitierten Rekonstruktion von Wellenfrontsegmenten beruhen, profitieren von der spezifischen Charakteristik dicker holographischer Gitter, welche als Bragg-Beugung basierte Volumengitter bezeichnet werden können. Es wird beschrieben, wie die Winkel-, Wellenlängen- und Polarisationsselektivität ausgelegt werden kann, um spezifische optische Funktionalitäten bereitzustellen. Diese sind unter anderem notwendig, um HD-fähige holographische 3D-Displays zu realisieren. Es wird eine kurze Einführung zu Hintergrundbeleuchtungseinheiten, komplexwertigen räumlichen Modulatoren und kombinierten Feldlinsen von holographischen 3D-Displays gegeben. Die Beschreibung Bragg-Beugung basierter Volumengitter erfolgt unter Nutzung der CWT (coupled wave theory). Es wird dargelegt, wie das 2-te Maximum der on-Bragg Modulation genutzt werden kann. Der Vorzug der 2-ten Bragg-Beugungsordnung wird erklärt. Polarisations-Strahlteiler-Geometrien werden beschrieben. Spezifische Anordnungen von holographischen 3D-Displays werden erklärt. Beleuchtungseinheiten und kombinierte Feldlinsen werden untersucht. Es wird beschrieben, wie die Unterdrückung diffraktiven Übersprechens erreicht werden kann.

    DigitalAngewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Patent

    Gerald Fütterer

    Display Device, in Particular a Head-Mounted Display, Based on Temporal and Spatial Multiplexing of Hologram Tiles

    2016

    DigitalAngewandte Naturwissenschaften und Wirtschaftsingenieurwesen

    Patent

    Gerald Fütterer

    Beam Divergence and Various Collimators for Holgraphic or Stereoscopic Displays

    2016