Dr. Jürgen Koch Profile

Dr. Jürgen Koch

at Laser Zentrum Hannover eV

SPIE Involvement:

Author

Publications (17)

Proceedings Article | 9 December 2021 Paper

A novel all-optical focused ultrasound detector for intravascular lipid imaging

Michael Nagli, Jürgen Koch, Yoav Hazan, Oleg Volodarsky, Resmi Ravi Kumar, Ahiad Levi, Evgeny Hahamovich, Ludger Overmeyer, Amir Rosenthal

Proceedings Volume 11923, 1192311 (2021) https://doi.org/10.1117/12.2615987

KEYWORDS: Sensors, Ultrasonography, Acoustics, Silicon, Optoacoustics, Signal detection, Optical sensors, Linear filtering, Waveguides, Spatial resolution

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Proceedings Article | 11 June 2021 Open Access

The MOONRISE: payload for mobile selective laser melting of lunar regolith

Jörg Neumann, Mathias Ernst, Patrick Taschner, Niklas Gerdes, Simon Stapperfend, Stefan Linke, Christoph Lotz, Jürgen Koch, Peter Wessels, Enrico Stoll, Ludger Overmeyer

Proceedings Volume 11852, 118526T (2021) https://doi.org/10.1117/12.2600322

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In-Situ Resource Utilization (ISRU) technologies pave the way for a sustainable colony on the Moon. Above all, the construction of structures using only the available resources is an important factor in reducing costs and logistical effort. The MOONRISE project aims to melt lunar regolith using lasers on mobile platforms for the Additive Manufacturing of structures. This process is called Mobile Selective Laser Melting (M-SLM) and has the advantage that only electrical energy and a moving system are required. In order to validate the laser melting of lunar regolith simulants on ground, a vacuum chamber was designed to host powder material at pressures of around 10-2 mbar. Laser exposure and high speed monitoring were performed through a window. Prior to finalizing the payload design, the type of laser source, appropriate spot size, power, and duration of exposure were determined by means of experimentation. For reasons of cost-efficiency, the payload development approach is to profit as much as possible from components commercial off-the-shelf (COTS), i.e. commercially available components, which have no formal space qualification. These components, e.g. built for automotive application, often withstand harsh environments or even have space heritage without the costly and long-lasting process of formal space qualification. For MOONRISE, COTS parts – partly based on space heritage - have been screened in environmental tests and selected for the payload. A detailed preliminary design review of the MOONRISE payload was conducted in 2019. The payload mainly consists of a printed circuit board (PCB) for system communication, a fiber coupled diode laser, an electrical diode driver, a beam focusing optics, and an LED illumination. For baseline operation, a laser power of typically 70W will be applied for 6s to the lunar surface at a distance of about 25cm. The LED illumination is supporting visualization of the molten regolith by external cameras. The MOONRISE payload can be accommodated to a rover or a robotic arm to ensure mobility for the melting experiments. Following that, an Engineering Model (EM) has been assembled and tested for functionality. The dimension of the payload is 1.5U CubeSat and it has a mass of about 2.5kg with further reduction potential towards flight model (FM) development. In the following steps, environmental tests, such as vibration and thermal-vacuum cycling, will be carried out with the EM. As laser melting of regolith under vacuum conditions produced dense material, tests were continued under low gravity conditions in the large-scale research device Einstein-Elevator at the Hannover Institute of Technology (HITec) of the Leibniz University Hannover (Germany), which is a further development of a classical drop tower with which experiments are carried out under conditions of microgravity [3]. It allows experiments under zero gravity conditions for about four seconds. The flight can be repeated up to 300 times per day. The Einstein-Elevator also enables adjustment of the gravity level from 0 to 5g, a feature that was used to carry out melting experiments with the EM under lunar gravitation conditions.

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Proceedings Article | 5 March 2021 Presentation

All-optical focused ultrasound detector for intravascular applications

Michael Nagli, Jürgen Koch, Yoav Hazan, Oleg Volodarsky, Resmi Ravi Kumar, Ahiad Levi, Evgeny Hahamovich, Ludger Overmeyer, Amir Rosenthal

Proceedings Volume 11642, 116421U (2021) https://doi.org/10.1117/12.2577228

KEYWORDS: Acoustics, Ultrasonography, Sensors, Glasses, Signal detection, Resonators, Laser resonators, Silicon, Signal generators, Signal attenuation

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Proceedings Article | 9 March 2020 Presentation

High quality Bessel beam generation through reflective axicon for femtosecond laser glass microprocessing (Conference Presentation)

Antonin Billaud, Maik Steinbach, Patrick Taschner, Arndt Hohnholz, Gwenn Pallier, Sami Laroui, Pu Jian, Olivier Pinel, Jürgen Koch, Guillaume Labroille

Proceedings Volume 11267, 112670C (2020) https://doi.org/10.1117/12.2545860

KEYWORDS: Bessel beams, Glasses, Reflectivity, Axicons, Femtosecond phenomena, Beam shaping, Pulsed laser operation, Laser ablation, Laser drilling, Dispersion

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Proceedings Article | 2 March 2020 Paper

Divide-and-conquer laser beam deflection system: Fast, wide-ranging, and flexible

Patrick Taschner, Jan Düsing, Jürgen Koch, Peter Jäschke, Stefan Kaierle, Ludger Overmeyer

Proceedings Volume 11268, 112681G (2020) https://doi.org/10.1117/12.2546162

KEYWORDS: Scanners, Laser sources, Laser ablation, Pulsed laser operation, Laser scanners, 3D scanning, Laser systems engineering, Modulation, Crystals, Polygon scanners

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Proceedings Article | 2 March 2020 Paper

Surface functionalization of flexographic printing forms using a femtosecond laser for adjustable material transfer in MID production processes

Alexander Wienke, Gerd-Albert Hoffmann, Jürgen Koch, Peter Jäschke, Ludger Overmeyer, Stefan Kaierle

Proceedings Volume 11267, 112670F (2020) https://doi.org/10.1117/12.2543544

KEYWORDS: Printing, Femtosecond phenomena, Waveguides, Laser scanners, Laser processing, Aerosols, Laser ablation, Data communications, Optics manufacturing

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Proceedings Article | 20 February 2012 Paper

Heat-induced structure formation in metal films generated by single ultrashort laser pulses

Jürgen Koch, Claudia Unger, Boris Chichkov

Proceedings Volume 8244, 824408 (2012) https://doi.org/10.1117/12.908561

KEYWORDS: Laser ablation, Gold, Pulsed laser operation, Metals, Ultrafast phenomena, Image processing, Scanning electron microscopy, Laser damage threshold, Phonons, Glasses

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Proceedings Article | 18 February 2010 Paper

Individually controlled multi-focus laser processing for two-photon polymerization

Kotaro Obata, Jürgen Koch, Boris Chichkov

Proceedings Volume 7584, 75840L (2010) https://doi.org/10.1117/12.842117

KEYWORDS: Two photon polymerization, Computer generated holography, Spatial light modulators, Laser processing, Phase modulation, Polymers, Diffractive optical elements, Switching, Scanning electron microscopy, Parallel processing

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Proceedings Article | 11 September 2006 Paper

Multiphoton laser lithography for the fabrication of plasmonic components

Sven Passinger, Jürgen Koch, Roman Kiyan, Carsten Reinhardt, Boris Chichkov

Proceedings Volume 6324, 63240U (2006) https://doi.org/10.1117/12.680418

KEYWORDS: Femtosecond phenomena, Plasmonics, Nanolithography, Photoresist materials, Dielectrics, Laser ablation, Gold, Lithography, Nanostructures, Nanowires

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Proceedings Article | 20 April 2006 Paper

Toward femtosecond laser lithography

J. Koch, E. Fadeeva, A. Ostendorf, B. Chichkov

Proceedings Volume 6195, 61950F (2006) https://doi.org/10.1117/12.660775

KEYWORDS: Femtosecond phenomena, Photoresist materials, Laser ablation, Lithography, Optical lithography, Photomasks, Photoresist developing, Pulsed laser operation, Maskless lithography, Super resolution

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Proceedings Article | 1 March 2006 Paper

Femtosecond laser lithography and applications

B. Chichkov, E. Fadeeva, J. Koch, A. Ostendorf, A. Ovsianikov, S. Passinger, C. Reinhardt

Proceedings Volume 6106, 610612 (2006) https://doi.org/10.1117/12.651664

KEYWORDS: Femtosecond phenomena, Photoresist materials, Two photon polymerization, Lithography, Polymers, Scanning electron microscopy, Tissues, Photonic crystals, Photosensitive materials, Laser systems engineering

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SPIE Journal Paper | 1 May 2005

Direct-write subwavelength structuring with femtosecond laser pulses

Jürgen Koch, Frank Korte, Carsten Fallnich, Andreas Ostendorf, Boris Chichkov

OE, Vol. 44, Issue 05, 051103, (May 2005) https://doi.org/10.1117/12.10.1117/1.1904053

KEYWORDS: Femtosecond phenomena, Laser ablation, Nanostructuring, Nanolithography, Metals, Pulsed laser operation, Nanostructures, Diffraction, Laser applications, Laser damage threshold

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Proceedings Article | 8 October 2004 Paper

Toward nanostructuring with femtosecond laser pulses

Juergen Koch, Takasumi Tanabe, Frank Korte, Carsten Fallnich, Andreas Ostendorf, Boris Chichkov

Proceedings Volume 5662, (2004) https://doi.org/10.1117/12.596773

KEYWORDS: Femtosecond phenomena, Nanostructuring, Nanolithography, Laser ablation, Metals, Nanostructures, Photons, Diffraction, Laser damage threshold, Laser systems engineering

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Proceedings Article | 20 September 2004 Open Access

Nanostructuring of solids with femtosecond laser pulses (Keynote Address)

Andreas Ostendorf, Juergen Koch, Frank Korte, Boris Chichkov

Proceedings Volume 5448, (2004) https://doi.org/10.1117/12.546496

KEYWORDS: Femtosecond phenomena, Nanostructuring, Nanolithography, Laser ablation, Nanostructures, Metals, Solids, Photons, Laser applications, Photonic crystals

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Proceedings Article | 29 April 2003 Paper

Toward nanostructuring with femtosecond laser pulses

Frank Korte, Juergen Koch, Carsten Fallnich, Andreas Ostendorf, Boris Chichkov

Proceedings Volume 5118, (2003) https://doi.org/10.1117/12.498496

KEYWORDS: Femtosecond phenomena, Nanolithography, Metals, Nanostructuring, Laser applications, Nanostructures, Laser damage threshold, Laser ablation, Pulsed laser operation, Diffraction

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Proceedings Article | 18 August 1997 Paper

Industrial aspects of precision machining with copper vapor lasers

Martin Hartmann, Juergen Koch, Adolf Lang, Karsten Schutte, Hans Bergmann

Proceedings Volume 3097, (1997) https://doi.org/10.1117/12.281083

KEYWORDS: Copper vapor lasers, Laser cutting, Laser drilling, Ceramics, Materials processing, Metals, Oscillators, Laser processing, Resonators, Pulsed laser operation

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The applications of conventional infrared lasers running cw or quasi-sw for drilling, cutting and shaping are limited in the precision achievable due to the long interaction time which leads to heat affected zones. The necessity to use a gas jet to blow the molten material out of the cut kerf will damage fragile workpieces like thin foils. Short laser pulses of sufficient intensity remove the material directly by evaporation and minimize the amount of heat transferred into the solid. Classical infrared laser sources generate a shielding air plasma within some ns at power densities above some 10⁷W/cm². The optical breakdown threshold value in air can be shifted to higher intensities by using visible light as well as reducing the focal diameter. An alternative way is to shorten the pulse duration to less than 10 ps that a plasma is generated only after the pulse. Thus, the material removal process begins after the deposition of the pulse energy into the material. But such short pulses will generate a pressure wave due to the sudden thermal expansion and can damage or destroy microscopic components. For industrial production the productivity is a further aspect. Hence, a certain mean power is required in order to obtain the desired production rate. Considering the above aspects, copper vapor lasers (CVLs) with ns pulse duration are well suited for precision machining of metals and ceramics. Processing with CVLs is an advantage in that its wavelength is highly absorbed by metallic targets and the probability for the optical breakdown in air is low. CVLs in an oscillator-amplifier-setup incorporate diffraction limited beam quality and high average power. The present paper outlines the potential of the CVL for the industrial use regarding high processing speed and precision. Under these aspects the limiting mechanisms on the material removal process and the necessary processing strategies for scaling up the productivity are shown. The relevant laser parameters for increasing the working speed and the relationship to the achievable precision are given. The design aspects of a copper vapor laser system with high mean output power and repetition rate are outlined. To conclude, several typical machining tasks, e.g. cutting of green foils, drilling of scimmer holes for thermal analysis are presented.

Proceedings Article | 4 April 1997 Paper

Copper vapor laser MOPA-chain for highly efficient and precise material removal

Karsten Schutte, Eric Gan, Juergen Koch, Adolf Lang, Martin Hartmann, Roland Mayerhofer, Tomas Slunecko, Hans Bergmann

Proceedings Volume 3092, (1997) https://doi.org/10.1117/12.270238

KEYWORDS: Copper vapor lasers, Laser drilling, Laser cutting, Metals, Resonators, Copper, Oscillators, Amplifiers, Materials processing, Pulsed laser operation

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Showing 5 of 17 publications

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