Dr. Ulrich Hofmann Profile

Dr. Ulrich Hofmann

CEO at OQmented GmbH

SPIE Involvement:

Author

Publications (26)

Proceedings Article | 13 March 2024 Presentation

MEMS and Laser based microdisplay light engine for AR

Ulrich Hofmann

Proceedings Volume 12914, 129140X (2024) https://doi.org/10.1117/12.3024902

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Proceedings Article | 7 March 2022 Presentation

Laser Scanning Based depth sensing and displaying for augmented reality

Ulrich Hofmann

Proceedings Volume 11932, 1193207 (2022) https://doi.org/10.1117/12.2632472

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Proceedings Article | 5 April 2021 Presentation

Oqmented: MEMS Based Laser Beam Scanning: The Key to Meeting Compactness and Performance Requirements of AR-smartglasses

Ulrich Hofmann

Proceedings Volume 11764, 117641N (2021) https://doi.org/10.1117/12.2598225

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Proceedings Article | 28 March 2021 Presentation + Paper

Laser beam scanning based AR-display applying resonant 2D MEMS mirrors

Oleg Petrak, Fabian Schwarz, Leon Pohl, Marcel Reher, Christian Janicke, Jan Przytarski, Frank Senger, Jörg Albers, Thorsten Giese, Lars Ratzmann, Peter Blicharski, Stephan Marauska, Thomas von Wantoch, Ulrich Hofmann

Proceedings Volume 11765, 1176503 (2021) https://doi.org/10.1117/12.2579695

KEYWORDS: Microelectromechanical systems, Mirrors, RGB color model, Projection systems, Laser sources, Control systems, Waveguides, Virtual reality, Video, Prototyping

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Proceedings Article | 5 March 2021 Presentation + Paper

Wide angle LiDAR demonstrator based on a resonantly operated 1D MEMS mirror capable of scanning 180°

Leon Pohl, Fabian Schwarz, Peter Blicharski, Christian Janicke, Oleg Petrak, Thomas von Wantoch, Ulrich Hofmann

Proceedings Volume 11697, 116970D (2021) https://doi.org/10.1117/12.2578151

KEYWORDS: LIDAR, Mirrors, Microelectromechanical systems, Electronics, Sensors, Scanners, Ranging, Piezoelectric drives, Laser sources, Infrared radiation

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Proceedings Article | 28 February 2020 Presentation + Paper

A bi-axial vacuum-packaged piezoelectric MEMS mirror for smart headlights

F. Senger, J. Albers, U. Hofmann, G. Piechotta, T. Giese, F. Heinrich, T. von Wantoch, S. Gu-Stoppel

Proceedings Volume 11293, 1129305 (2020) https://doi.org/10.1117/12.2542802

KEYWORDS: Microelectromechanical systems, Mirrors, Semiconducting wafers, Wafer bonding, Actuators, Aluminum nitride, Headlamps, Glasses, Silicon, Molybdenum

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Proceedings Article | 28 February 2020 Paper

Resonant 1D MEMS mirror with a total optical scan angle of 180° for automotive LiDAR

Fabian Schwarz, Frank Senger, Jörg Albers, Pauline Malaurie, Christian Janicke, Leon Pohl, Felix Heinrich, Dirk Kaden, Hans-Joachim Quenzer, Fabian Lofink, Andreas Bahr, Thomas von Wantoch, Ulrich Hofmann

Proceedings Volume 11293, 1129309 (2020) https://doi.org/10.1117/12.2546035

KEYWORDS: Mirrors, Microelectromechanical systems, Scanners, LIDAR, Semiconducting wafers, Sensors, Glasses, Laser scanners, Humidity, 3D scanning

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Proceedings Article | 15 March 2016 Paper

Modeling of biaxial gimbal-less MEMS scanning mirrors

Thomas von Wantoch, Shanshan Gu-Stoppel, Frank Senger, Christian Mallas, Ulrich Hofmann, Thomas Meurer, Wolfgang Benecke

Proceedings Volume 9760, 976008 (2016) https://doi.org/10.1117/12.2213518

KEYWORDS: Mirrors, Microelectromechanical systems, Finite element methods, Scanners, Micromirrors, Computing systems, Modeling, Laser scanners, Systems modeling, Piezoelectric drives, Piezoelectric thin film actuators, 3D modeling, Control systems, Actuators

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Proceedings Article | 27 February 2015 Paper

Centimeter-scale MEMS scanning mirrors for high power laser application

F. Senger, U. Hofmann, Thomas von Wantoch, C. Mallas, J. Janes, W. Benecke, Patrick Herwig, P. Gawlitza, Moises Ortega Delgado, C. Grune, J. Hannweber, A. Wetzig

Proceedings Volume 9375, 937509 (2015) https://doi.org/10.1117/12.2079600

KEYWORDS: Mirrors, Microelectromechanical systems, Semiconducting wafers, High power lasers, Laser applications, Scanners, Modulation, Electrodes, Laser scanners, 3D scanning

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Proceedings Article | 27 February 2015 Paper

Piezoelectrically driven translatory optical MEMS actuator with 7mm apertures and large displacements

H.- Quenzer, S. Gu-Stoppel, F. Stoppel, J. Janes, U. Hofmann, W. Benecke

Proceedings Volume 9375, 93750O (2015) https://doi.org/10.1117/12.2077101

KEYWORDS: Mirrors, Actuators, Spectrometers, FT-IR spectroscopy, Ferroelectric materials, Doppler effect, Semiconducting wafers, Microopto electromechanical systems, Silicon, Microelectromechanical systems

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Proceedings Article | 7 March 2014 Paper

Two-dimensional scanning using two single-axis low-voltage PZT resonant micromirrors

S. Gu-Stoppel, J. Janes, H. Quenzer, U. Hofmann, W. Benecke

Proceedings Volume 8977, 897706 (2014) https://doi.org/10.1117/12.2036565

KEYWORDS: Micromirrors, Mirrors, Ferroelectric materials, Actuators, Silicon, Electromagnetism, Polarization, Finite element methods, Laser sources, Laser based displays

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Proceedings Article | 7 March 2014 Paper

Analysis of capacitive sensing for 2D-MEMS scanner laser projection

Thomas von Wantoch, Christian Mallas, Ulrich Hofmann, Joachim Janes, Bernhard Wagner, Wolfgang Benecke

Proceedings Volume 8977, 897707 (2014) https://doi.org/10.1117/12.2038606

KEYWORDS: Capacitance, Micromirrors, Sensors, Mathematical modeling, Electrodes, Laser scanners, 3D scanning, Microelectromechanical systems, Analog electronics, Scanners

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Proceedings Article | 7 March 2014 Paper

Wafer-level vacuum-packaged two-axis MEMS scanning mirror for pico-projector application

Ulrich Hofmann, Frank Senger, Joachim Janes, Christian Mallas, Vanessa Stenchly, Thomas von Wantoch, Hans-Joachim Quenzer, Manfred Weiss

Proceedings Volume 8977, 89770A (2014) https://doi.org/10.1117/12.2038249

KEYWORDS: Mirrors, Microelectromechanical systems, Packaging, Glasses, Semiconducting wafers, Laser based displays, Electrodes, Modulation, High power lasers, Oscillators

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Proceedings Article | 7 March 2014 Paper

Studies on the dynamics of vacuum encapsulated 2D MEMS scanners by laser Doppler vibrometry

Joachim Janes, Ulrich Hofmann

Proceedings Volume 8975, 89750H (2014) https://doi.org/10.1117/12.2037182

KEYWORDS: Microelectromechanical systems, Mirrors, Scanners, Laser scanners, 3D scanning, Doppler effect, Vibrometry, Glasses, Semiconducting wafers, Micromirrors

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SPIE Journal Paper | 2 December 2013

Resonant biaxial 7-mm MEMS mirror for omnidirectional scanning

Ulrich Hofmann, Mika Aikio, Joachim Janes, Frank Senger, Vanessa Stenchly, Juergen Hagge, Hans-Joachim Quenzer, Manfred Weiss, Thomas von Wantoch, Christian Mallas, Bernhard Wagner, Wolfgang Benecke

JM3, Vol. 13, Issue 01, 011103, (December 2013) https://doi.org/10.1117/12.10.1117/1.JMM.13.1.011103

KEYWORDS: Mirrors, Microelectromechanical systems, Laser scanners, Roads, Sensors, Laser development, Packaging, Wafer bonding, Actuators

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Proceedings Article | 13 March 2013 Paper

Resonant biaxial 7-mm MEMS mirror for omnidirectional scanning

U. Hofmann, M. Aikio, J. Janes, F. Senger, V. Stenchly, M. Weiss, H.-J. Quenzer, B. Wagner, W. Benecke

Proceedings Volume 8616, 86160C (2013) https://doi.org/10.1117/12.2006189

KEYWORDS: Mirrors, Microelectromechanical systems, Semiconducting wafers, Sensors, Glasses, Silicon, Packaging, Wafer bonding, Wafer-level optics, Neodymium

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Proceedings Article | 9 March 2013 Paper

Piezoelectric resonant micromirror with high frequency and large deflection applying mechanical leverage amplification

S. Gu-Stoppel, J. Janes, D. Kaden, H. Quenzer, U. Hofmann, W. Benecke

Proceedings Volume 8612, 86120I (2013) https://doi.org/10.1117/12.2001620

KEYWORDS: Micromirrors, Actuators, Ferroelectric materials, Mirrors, Finite element methods, Electromagnetism, Silicon, Thin films, Silica, Microelectromechanical systems

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Proceedings Article | 5 March 2013 Paper

New fabrication method of glass packages with inclined optical windows for micromirrors on wafer level

Vanessa Stenchly, Hans-Joachim Quenzer, Ulrich Hofmann, Joachim Janes, Björn Jensen, Wolfgang Benecke

Proceedings Volume 8613, 861319 (2013) https://doi.org/10.1117/12.2001760

KEYWORDS: Glasses, Semiconducting wafers, Silicon, Mirrors, Micromirrors, Wafer-level optics, Wafer bonding, Packaging, Surface roughness

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For many applications it is inevitable to protect MEMS devices against environmental impacts like humidity which can affect their performance. Moreover recent publications demonstrates that micro mirrors can achieve very large optical scan angles at moderate driving voltages even exceeding 100 degrees when hermetically sealed under vacuum. While discrete chips may be evacuated and sealed on single die level using small can packages like TO housings, it is obvious that for high volume production a much more economical solution for the realisation of transparent optical packages already on wafer level must be developed. However, since any laser beam crossing a transparent glass surface is partly reflected even when anti-reflective coatings are applied, the construction of a wafer level optical housing suitable for laser projection purpose requires more than the integration of simple plane glass cap. The use of inclined optical windows avoids the occurrence of intense reflections of the incident laser beam in the projected images. This paper describes a unique technology to fabricate glass packages with inclined optical windows for micro mirrors on 8 inch wafers. The new process uses a high temperature glass forming process based on subsequent wafer bonding. A borosilicate glass wafer is bonded together with two structured silicon wafers. By grinding both sides of the wafer stack, a pattern of isolated silicon structures is defined. This preprocessed glass wafer is bonded thereon on a third structured silicon wafer, wherein the silicon islands are inserted into the cavities. By setting a defined pressure level inside the cavities during the final wafer bonding, the silicon glass stack extruded and it is out of plane during a subsequent annealing process at temperatures above the softening point of the glass. Finally the silicon is selectively removed in a wet etching process. This technique allows the fabrication of 8 inch glass wafers with oblique optical surfaces with surface roughness <1 nm and an evenness of < 300 nm.

Proceedings Article | 14 February 2011 Paper

MEMS scanning laser projection based on high-Q vacuum packaged 2D-resonators

U. Hofmann, C. Eisermann, H.-J. Quenzer, J. Janes, C. Schroeder, O. Schwarzelbach, B. Jensen, L. Ratzmann, T. Giese, F. Senger, J. Hagge, M. Weiss, B. Wagner, W. Benecke

Proceedings Volume 7930, 79300R (2011) https://doi.org/10.1117/12.878676

KEYWORDS: Mirrors, Microelectromechanical systems, Semiconducting wafers, Glasses, Scanners, Silicon, Wafer bonding, Packaging, Electrodes

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Proceedings Article | 26 February 2008 Paper

A novel fabrication technology for anti-reflex wafer-level vacuum packaged microscanning mirrors

M. Oldsen, U. Hofmann, H. J. Quenzer, J. Janes, C. Stolte, K. Gruber, M. Ites, F. Sörensen, B. Wagner

Proceedings Volume 6882, 688208 (2008) https://doi.org/10.1117/12.760941

KEYWORDS: Semiconducting wafers, Mirrors, Wafer bonding, Silicon, Glasses, Scanners, Oxides, Optical resolution, Micromirrors, Gold

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Proceedings Article | 21 February 2008 Paper

Wafer-level vacuum packaged resonant micro-scanning mirrors for compact laser projection displays

Ulrich Hofmann, Marten Oldsen, Hans-Joachim Quenzer, Joachim Janes, Martin Heller, Manfred Weiss, Georgios Fakas, Lars Ratzmann, Eleonora Marchetti, Francesco D'Ascoli, Massimiliano Melani, Luca Bacciarelli, Emilio Volpi, Francesco Battini, Luca Mostardini, Francesco Sechi, Marco De Marinis, Bernd Wagner

Proceedings Volume 6887, 688706 (2008) https://doi.org/10.1117/12.763433

KEYWORDS: Mirrors, Semiconducting wafers, Micromirrors, Silicon, Microelectromechanical systems, Laser based displays, Packaging, Scanners, Raster graphics, Sensors

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Proceedings Article | 14 October 2003 Paper

A laser-scanning endoscope based on polysilicon micromachined mirrors with enhanced attributes

Markus George, Hansjoerg Albrecht, Marc Schurr, Panagiotis Papageorgas, Ulrich Hofmann, Dimitris Maroulis, Christian Depeursinge, Dimitris Iakkovidis, Nikiforos Theofanous, Arianna Menciassi

Proceedings Volume 5143, (2003) https://doi.org/10.1117/12.500541

KEYWORDS: Endoscopes, Mirrors, Endoscopy, Head, Laser scanners, Scanners, Neural networks, Video, Tissues, Beam splitters

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Proceedings Article | 9 April 2003 Paper

Laser-scanning endoscope with enhanced attributes

Nikiforos Theofanous, G. Markus, Christian Depeursinge, D. Maroulis, Panagiotis Papageorgas, Hansjoerg Albrecht, Ulrich Hofmann, Arianna Menciassi

Proceedings Volume 5131, (2003) https://doi.org/10.1117/12.513682

KEYWORDS: Endoscopes, Modulation transfer functions, Mirrors, Signal detection, Laser scanners, Beam splitters, Spatial frequencies, Laser tissue interaction, Optical fibers, Image quality

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Proceedings Article | 2 September 1999 Paper

Electrostatically driven micromirrors for a miniaturized confocal laser scanning microscope

Ulrich Hofmann, Sascha Muehlmann, Martin Witt, Klaus Doerschel, Rijk Schuetz, Bernd Wagner

Proceedings Volume 3878, (1999) https://doi.org/10.1117/12.361269

KEYWORDS: Mirrors, Micromirrors, Silicon, Nickel, Electrodes, Laser scanners, Microscopes, Confocal microscopy, Scanners, Image resolution

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Proceedings Article | 31 August 1999 Paper

Progress in gray-tone lithography and replication techniques for different materials

Klaus Reimer, R. Engelke, Ulrich Hofmann, P. Merz, Klaus Kohlmann-von Platen, Bernd Wagner

Proceedings Volume 3879, (1999) https://doi.org/10.1117/12.360514

KEYWORDS: Lithography, Silicon, Photomasks, Etching, Metals, Chromium, Diffractive optical elements, Infrared radiation, Reflectivity, Mirrors

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Proceedings Article | 2 September 1997 Paper

Fabrication of microrelief surfaces using a one-step lithography process

Klaus Reimer, Ulrich Hofmann, M. Juerss, Wolfgang Pilz, Hans Joachim Quenzer, Bernd Wagner

Proceedings Volume 3226, (1997) https://doi.org/10.1117/12.284557

KEYWORDS: Lithography, Photoresist processing, Etching, Silicon, Lenses, Dry etching, Control systems, Micromachining, Anisotropic etching, Binary data

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