Dr. Rainer C. Wilhelm Profile

Dr. Rainer C. Wilhelm

at Fogale Nanotech

SPIE Involvement:

Author

Publications (35)

Proceedings Article | 20 November 2017 Open Access

EUCLID mission baseline design

Oswald Wallner, Klaus Ergenzinger, Rainer Wilhelm, Ludovic Vaillon

Proceedings Volume 10564, 105640R (2017) https://doi.org/10.1117/12.2309034

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Proceedings Article | 17 July 2008 Paper

Active Phasing Experiment: preliminary results and prospects

F. Gonte, C. Araujo, R. Bourtembourg, R. Brast, F. Derie, P. Duhoux, C. Dupuy, C. Frank, R. Karban, R. Mazzoleni, L. Noethe, I. Surdej, N. Yaitskova, R. Wilhelm, B. Luong, E, Pinna, S. Chueca, A. Vigan

Proceedings Volume 7012, 70120Z (2008) https://doi.org/10.1117/12.790342

KEYWORDS: Sensors, Telescopes, Mirrors, Segmented mirrors, Adaptive optics, Metrology, Control systems, Active optics, Large telescopes, Image segmentation

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Proceedings Article | 10 July 2008 Paper

Optical phasing of a segmented mirror with sub-nanometer precision: experimental results of the APE Internal Metrology

Rainer Wilhelm, Bruno Luong, Alain Courteville, Sébastien Estival, Frédéric Gonté

Proceedings Volume 7012, 701212 (2008) https://doi.org/10.1117/12.787377

KEYWORDS: Metrology, Mirrors, Segmented mirrors, Calibration, Charge-coupled devices, Cameras, Sensors, Interferometry, Image segmentation, Actuators

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Proceedings Article | 18 June 2007 Paper

On-axis, non-contact measurement of glass thicknesses and airgaps in optical systems with submicron accuracy

Rainer Wilhelm, Alain Courteville, Fabrice Garcia, François de Vecchi

Proceedings Volume 6616, 66163P (2007) https://doi.org/10.1117/12.725972

KEYWORDS: Distance measurement, Collimators, Optical testing, Interferometry, Optics manufacturing, Metrology, Mirrors, Interferometers, Laser metrology, Sensors

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This paper presents the fibre-optics low coherence interferometric sensor LISE and its applications in the optics manufacturing industry. The sensor works as a comparator of optical group delays. The group delay along the optical axis of the probe interferometer arm containing an object, for example a lens assembly, is compared with the group delay of the reference arm containing a movable delay line. The light source is a super luminescent diode (SLD) emitting at 1.31 &mgr;m with a coherence length of typically 25 &mgr;m. Thanks to the limited temporal coherence of the source, multiple surfaces of the object can be detected during a single scan of the delay line. Measurement ranges are between a few mm up to 600 mm (optical thickness). The measurement range can be placed at a working distance of up to several meters away from the instrument's exit. Two classes of accuracy exist. While the standard system has an absolute accuracy of ±1 &mgr;m for position and distance measurements, the second generation, high-accuracy system reaches an accuracy of better than ±200 nm for distance measurements while maintaining the ±1 &mgr;m accuracy for position measurements. The paper starts by explaining the measurement principle in Section 1. The following Section 2 describes the system design and the individual system components. The definition and validation of the absolute accuracy are discussed in Section 3, followed by a description of the complete detection procedure for the high accuracy system in Section 4. In its final Section 5 the paper gives examples of applications in the optics manufacturing industry. This description ranges from the centre thickness measurement of lenses to the "global" on-axis metrology of completely mounted optical systems such as objectives where all lens thicknesses and airgaps are measured without touching or disassembling the optical system. Practical considerations concerning alignment, focusing of the measurement beam, model-based signal identification, dispersion and longitudinal resolution are discussed.

Proceedings Article | 14 May 2007 Paper

On-axis, non-contact measurement of glass thicknesses and airgaps in optical systems with submicron accuracy

Rainer Wilhelm, Alain Courteville, Fabrice Garcia, François de Vecchi

Proceedings Volume 10316, 103160X (2007) https://doi.org/10.1117/12.723546

KEYWORDS: Collimators, Optics manufacturing, Metrology, Sensors, Optical testing, Interferometers, Signal detection, Interferometry, Mirrors, Glasses

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Proceedings Article | 15 September 2006 Paper

A novel low-coherence fibre optic interferometer for position and thickness measurements with unattained accuracy

Alain Courteville, Rainer Wilhelm, Fabrice Garcia

Proceedings Volume 6341, 63411Q (2006) https://doi.org/10.1117/12.695458

KEYWORDS: Distance measurement, Interferometers, Mirrors, Interferometry, Glasses, Semiconducting wafers, Zerodur, Metrology, Signal detection, Fiber optics

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This paper presents the second generation LISE-LI of the fibre-optics Low coherence Interferometric Sensor (LISE), recently developed by FOGALE nanotech. Based on the proven concept of low coherence interferometry, the LISE system works as a comparator of optical group delays. The group delay along the optical axis in the probe interferometer arm containing the object to be measured is compared with the group delay along the optical axis of the reference interferometer arm containing a delay line. The latter consists of a mirror that can be linearly displaced on a translation stage. The light source is a super luminescent diode emitting at a near infrared wavelength (typically 1.31 μm) with a spectral bandwidth of a few tens of nm. Thanks to the limited temporal coherence of the source, multiple surfaces of the object can be detected during a single scan of the delay line. Measurement ranges are between a few mm up to 600 mm (optical thickness). The measurement zone can be placed at a working distance of up to several meters away from the instrument's exit. Applications in industry and in research laboratories include thickness measurements of individual optical elements (e.g. lenses), technical multi-layer glasses, display cover glasses, semiconductor wafers, and position measurements of multiple elements of an optical system (e.g. a photographic lens). Compared to the first generation of the system, the absolute accuracy of the second generation system is about ten times better, reaching a level of ±100 nm for thickness measurements over the full measurement range. Following an introductory description of the measurement principle, the first part of the paper focuses on the key elements in the system design, both in hardware and detection algorithm, that ensure the high accuracy level. The second part of the paper presents an experimental validation of the achieved accuracy level. We present results of thickness measurements on distance pieces made of Zerodur. The measured results demonstrate the absolute accuracy over the measurement range as well as the excellent long-term stability of the system.

Proceedings Article | 26 June 2006 Paper

The active phasing experiment: Part II. Design and developments

F. Gonte, N. Yaitskova, F. Derie, C. Araujo, R. Brast, B. Delabre, P. Dierickx, C. Dupuy, C. Frank, S. Guisard, R. Karban, L. Noethe, B. Sedghi, I. Surdej, R. Wilhelm, M. Reyes, S. Esposito, M. Langlois

Proceedings Volume 6267, 626730 (2006) https://doi.org/10.1117/12.672057

KEYWORDS: Sensors, Telescopes, Mirrors, Segmented mirrors, Image segmentation, Metrology, Control systems, Device simulation, Electronics, Charge-coupled devices

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Proceedings Article | 23 June 2006 Paper

Shape measurements of a segmented mirror with nanometer accuracy: the APE internal metrology

Rainer Wilhelm, Alain Courteville, Sébastien Estival, Alexis Bietti, Virginie Seiller, Frédéric Gonté

Proceedings Volume 6267, 626731 (2006) https://doi.org/10.1117/12.672780

KEYWORDS: Charge-coupled devices, Mirrors, Interferometry, Light sources, Calibration, Metrology, Segmented mirrors, Interferometers, Modulators, Phase measurement

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Proceedings Article | 25 April 2006 Paper

A novel low coherence fibre optic interferometer for position and thickness measurements with unattained accuracy

Rainer Wilhelm, Alain Courteville, Fabrice Garcia

Proceedings Volume 6189, 618918 (2006) https://doi.org/10.1117/12.663654

KEYWORDS: Distance measurement, Interferometry, Interferometers, Mirrors, Zerodur, Laser metrology, Glasses, Refractive index, Interfaces, Optical testing

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This paper presents the second generation LISE-LI of the fibre-optics Low coherence Interferometric Sensor (LISE), recently developed by FOGALE nanotech. Based on the proven concept of partial coherence interferometry, the LISE system works as a comparator of optical group delays. The group delay along the optical axis in the probe interferometer arm containing the object to be measured is compared with the group delay along the optical axis of the reference interferometer arm containing a delay line. The latter consists of a mirror that can be linearly displaced on a translation stage. The light source is a super luminescent diode emitting at near infrared wavelength (typically 1.31 μm) with a spectral bandwidth of a few tens of nm. Thanks to the limited temporal coherence of the source, multiple surfaces of the object can be detected during a single scan of the delay line. Measurement ranges are between a few mm up to 600 mm (optical thickness). The measurement zone can be placed at a working distance of up to several meters away from the instrument's exit. Applications in industry and in research laboratories include thickness measurements of individual optical elements (e.g. lenses), technical multi-layer glasses, glue and varnish layers deposited on various substrates, Si or GaAs wafers, and position measurements of multiple elements of an optical system (e.g. a photographic lens). Compared to the first generation of the system, the absolute accuracy of the second generation system is about ten times better, reaching a level of ±100 nm for thickness measurements over the full measurement range. Following an introductory description of the measurement principle, the first part of the paper focuses on the key elements in the system design, both in hardware and detection algorithm, that ensure the high accuracy level. The second part of the paper presents an experimental validation of the achieved accuracy level. We present results of thickness measurements on distance pieces made of Zerodur^®. The measured results demonstrate the absolute accuracy over the measurement range as well as the excellent long-term stability of the system.

Proceedings Article | 20 October 2005 Paper

Contact-free on-axis metrology for the fabrication and testing of complex optical systems

Alain Courteville, Rainer Wilhelm, Marie Delaveau, Fabrice Garcia, François de Vecchi

Proceedings Volume 5965, 596510 (2005) https://doi.org/10.1117/12.625200

KEYWORDS: Metrology, Interferometry, Interferometers, Collimators, Interfaces, Signal processing, Optical testing, Sensors, Distance measurement, Mirrors

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This paper presents a fibre-based low coherence interferometric sensor developed by FOGALE nanotech. Based on the proven principle of partial coherence interferometry the sensor works as a comparator of optical path lengths. The optical path lengths along the optical axis in the measurement interferometer arm containing a target object are compared with the optical path lengths in an internal delay line. Multiple, partially reflecting surfaces of the target can be detected during one scan of the delay line. Standard measurement ranges are between a few mm up to 400 mm (optical thickness). Longer measurement ranges are available on request. The measurement zone can be placed at a distance of up to several meters away from the instrument's exit. The sensor reaches an absolute accuracy on position measurements down to ±100 nm over the full measurement range. The system has been successfully applied in industry (glass and optical) as well as in research environments, e.g. for the dimensional metrology of large astronomical telescopes. This paper focuses on an innovative application of the sensor in the optics manufacturing industry. The paper starts with a description of the measurement technique, the system hardware concept, the detection and signal processing scheme. We present a modeling-based approach for the dimensional metrology of optical components (e.g. single lenses, windows, prisms) or complete, mounted systems where the positions of all individual elements can be detected. A comprehensive propagation model including dispersion and phase effects is used to extract the distances from the optical path differences. Prior to a measurement, the optimum tailoring of the measurement beam is obtained by a simulation of the beam propagation through the target object. This ensures that each surface to be measured delivers a sufficiently strong signal. To illustrate our approach we present its application in the fabrication process of complex optical systems where "global" metrology of complete systems can be performed with a very high accuracy in a short time.

Proceedings Article | 18 August 2005 Paper

APE: the Active Phasing Experiment to test new control system and phasing technology for a European Extremely Large Optical Telescope

F. Gonte, N. Yaitskova, F. Derie, C. Araujo, R. Brast, B. Buzzoni, B. Delabre, P. Dierickx, C. Dupuy, R. Esteves, C. Frank, S. Guisard, R. Karban, E. Koenig, J. Kolb, M. Nylund, L. Noethe, I. Surdej, A. Courteville, R. Wilhelm, L. Montoya, M. Reyes, S. Esposito, E. Pinna, K. Dohlen, M. Ferrari, M. Langlois

Proceedings Volume 5894, 58940Z (2005) https://doi.org/10.1117/12.616925

KEYWORDS: Image segmentation, Sensors, Segmented mirrors, Telescopes, Control systems, Mirrors, Stars, Metrology, Cameras, Active optics

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Proceedings Article | 13 June 2005 Paper

Dimensional metrology for the fabrication of imaging optics using a high accuracy low coherence interferometer

Rainer Wilhelm, Alain Courteville, Fabrice Garcia

Proceedings Volume 5856, (2005) https://doi.org/10.1117/12.612563

KEYWORDS: Interferometers, Interferometry, Metrology, Interfaces, Collimators, Mirrors, Signal processing, Sensors, Signal detection, Coherence (optics)

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Proceedings Article | 20 October 2004 Paper

Influence of atmospheric turbulence on the performance and design of GENIE

Olivier Absil, Roland den Hartog, Philippe Gondoin, Pierre Fabry, Luigi d'Arcio, Rainer Wilhelm, Philippe Gitton, Florence Puech

Proceedings Volume 5491, (2004) https://doi.org/10.1117/12.550441

KEYWORDS: Interferometers, Atmospheric turbulence, Dispersion, L band, Nulling interferometry, Telescopes, Wavefronts, Photons, Servomechanisms, Actuators

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Proceedings Article | 20 October 2004 Paper

VLTI technical advances: present and future

Andreas Glindemann, Maja Albertsen, Luigi Andolfato, Gerardo Avila, Pascal Ballester, Bertrand Bauvir, Francoise Delplancke, Frederic Derie, Martin Dimmler, Philippe Duhoux, Emmanuel di Folco, R. Frahm, Emmanuel Galliano, Bruno Gilli, Paul Giordano, Philippe Gitton, Stephane Guisard, Nico Housen, Christian Hummel, Alexis Huxley, Robert Karban, Pierre Kervella, Mario Kiekebusch, Bertrand Koehler, Samuel Leveque, Tom Licha, Antonio Longinotti, Derek McKay, Serge Menardi, Guy Monnet, Sebastien Morel, Francesco Paresce, Isabelle Percheron, Monika Petr-Gotzens, Thanh Phan Duc, Joerg-Uwe Pott, Florence Puech, Fredrik Rantakyro, Andrea Richichi, Cyrus Sabet, Kevin Scales, Markus Schoeller, N. Schuhler, Mario van den Ancker, Martin Vannier, Anders Wallander, Markus Wittkowski, Rainer Wilhelm

Proceedings Volume 5491, (2004) https://doi.org/10.1117/12.551468

KEYWORDS: Telescopes, Stars, Interferometry, Sensors, Adaptive optics, Astatine, Observatories, Near infrared, Mid-IR, IRIS Consortium

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Proceedings Article | 20 October 2004 Paper

Darwin-GENIE: a nulling instrument at the VLTI

Philippe Gondoin, Olivier Absil, Roland den Hartog, Rainer Wilhelm, Philippe Gitton, Luigi d'Arcio, Pierre Fabry, Florence Puech, Malcolm Fridlund, Markus Schoeller, Andreas Glindemann, Eric Bakker, Anders Karlsson, Anthony Peacock, S. Volonte, Francesco Paresce, Andrea Richichi

Proceedings Volume 5491, (2004) https://doi.org/10.1117/12.549411

KEYWORDS: Interferometers, Stars, Telescopes, Nulling interferometry, Planets, Space telescopes, Clouds, Infrared radiation, L band, Mid-IR

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Proceedings Article | 20 October 2004 Paper

The simulated detection of low-mass companions with GENIE

Roland den Hartog, Olivier Absil, Philippe Gondoin, Luigi d'Arcio, Pierre Fabry, Lisa Kaltenegger, Rainer Wilhelm, Philippe Gitton, Florence Puech, C. V. Fridlund

Proceedings Volume 5491, (2004) https://doi.org/10.1117/12.552563

KEYWORDS: Planets, Modulation, Stars, Signal to noise ratio, Nulling interferometry, Calibration, Signal detection, Phase shift keying, Interferometers, Infrared telescopes

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Proceedings Article | 16 September 2004 Paper

FINCH: time-dependent simulation of nulling interferometry for the DARWIN mission

Klaus Ergenzinger, Michael Kersten, Rainer Sesselmann, Raphael Schwarz, Ulrich Johann, Rainer Wilhelm, Kevin Scales, Christian Erd

Proceedings Volume 5497, (2004) https://doi.org/10.1117/12.552593

KEYWORDS: Optical simulations, Nulling interferometry, Interferometers, Wavefronts, Optical filters, Matrices, Beam propagation method, Modeling, Fiber couplers, Navigation systems

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Proceedings Article | 16 September 2004 Paper

The VLTI integrated model: a precursor model for integrated modeling of future telescopes

Michael Mueller, Rainer Wilhelm, Kevin Scales, Horst Baier

Proceedings Volume 5497, (2004) https://doi.org/10.1117/12.551484

KEYWORDS: Integrated modeling, Telescopes, Interferometers, Wavefronts, Systems modeling, Optical fibers, Simulink, Control systems, Polarization, Integrated optics

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Proceedings Article | 7 July 2004 Paper

Integrated modeling for the VLTI

Michael Muller, Rainer Wilhelm, Horst Baier, Franz Koch

Proceedings Volume 5382, (2004) https://doi.org/10.1117/12.566226

KEYWORDS: Integrated modeling, Telescopes, Interferometers, Motion models, Geometrical optics, Mirrors, Finite element methods, Data modeling, Control systems, Device simulation

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