Dr. Nils J. Krichel Profile

Dr. Nils J. Krichel

Senior Development Engineer at Helia Photonics Ltd

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Publications (7)

Proceedings Article | 10 October 2012 Paper

Depth imaging at kilometer range using time-correlated single-photon counting at wavelengths of 850 nm and 1560 nm

Gerald Buller, Aongus McCarthy, Ximing Ren, Nathan Gemmell, Robert Collins, Nils Krichel, Michael Tanner, Andrew Wallace, Sandor Dorenbos, Val Zwiller, Robert Hadfield

Proceedings Volume 8460, 84601I (2012) https://doi.org/10.1117/12.965890

KEYWORDS: Imaging systems, Single photon, Signal to noise ratio, Sensors, Profiling, Picosecond phenomena, Single photon detectors, Avalanche photodiodes, LIDAR, Nanowires

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Proceedings Article | 16 September 2011 Paper

Kilometer range depth imaging using time-correlated single-photon counting

Gerald Buller, Nils Krichel, Aongus McCarthy, Nathan Gemmell, Michael Tanner, Chandra Natarajan, Ximing Ren, Robert Hadfield

Proceedings Volume 8155, 81551I (2011) https://doi.org/10.1117/12.899377

KEYWORDS: Single photon detectors, Sensors, Data acquisition, Imaging systems, LIDAR, Semiconductor lasers, Radar, Range imaging, Picosecond phenomena, Silicon

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Proceedings Article | 24 January 2011 Paper

Single-photon detection in time-of-flight-depth imaging and quantum key distribution

Gerald Buller, Robert Collins, Patrick Clarke, Nils Krichel, Aongus McCarthy, Ryan Warburton, Frauke Izdebski, Robert Hadfield

Proceedings Volume 7945, 79452M (2011) https://doi.org/10.1117/12.873808

KEYWORDS: Sensors, Quantum key distribution, Single photon detectors, Quantum communications, Optical fibers, Silicon, Information security, Avalanche photodiodes, Ranging, Data acquisition

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Proceedings Article | 18 August 2010 Paper

Long-range depth imaging using time-correlated single-photon counting

Nils Krichel, Aongus McCarthy, Andrew Wallace, Jing Ye, Gerald Buller

Proceedings Volume 7780, 77801I (2010) https://doi.org/10.1117/12.876144

KEYWORDS: Sensors, Detection and tracking algorithms, Target detection, Target acquisition, Data acquisition, Imaging systems, Single photon detectors, Signal to noise ratio, Data analysis, 3D image processing

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Proceedings Article | 21 April 2010 Paper

Anti-aliasing techniques in photon-counting depth imaging using GHz clock rates

Nils Krichel, Aongus McCarthy, Robert Collins, Gerald Buller

Proceedings Volume 7681, 768108 (2010) https://doi.org/10.1117/12.850900

KEYWORDS: Ranging, Clocks, Imaging systems, Target detection, Target acquisition, Single photon detectors, Pulsed laser operation, Semiconductor lasers, Data acquisition, Photodetectors

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Proceedings Article | 19 September 2009 Paper

Scanning of low-signature targets using time-correlated single-photon counting

Nils Krichel, Aongus McCarthy, Robert Collins, Verónica Fernández, Andrew Wallace, Gerald Buller

Proceedings Volume 7482, 748202 (2009) https://doi.org/10.1117/12.829362

KEYWORDS: Photons, Mirrors, Data acquisition, Signal to noise ratio, Imaging systems, Semiconductor lasers, Signal attenuation, Target acquisition, Transceivers, Cameras

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This paper presents recent progress in the development of a scanning time-of-flight imaging system employing time-correlated single-photon counting (TCSPC) designed for the acquisition of depth information at kilometre ranges. The device is capable of acquiring information on non-cooperative target surfaces at eye-safe average optical power levels in the near-IR regime (<1 mW at 842 nm illumination wavelength). Target illumination is periodic or non-periodic at typical repetition frequencies in the MHz domain, utilising a sub-ns pulse-width laser diode. The system output is steered over the optical field of interest, and return photons from the target are routed towards a single-photon detector. Measurements are performed with a silicon single-photon avalanche diode (SPAD). Effective optical spatial and spectral filtering techniques permit operation in bright daylight conditions. Results in the form of depth images from a variety of targets, taken under various environmental conditions, are presented. Achieved improvements of this first-generation system are discussed in terms of parametric enhancement of quantities such as spatial and spectral filtering, internal optical attenuation and beam size. We detail progress in the design process both based on theoretical assumptions and actual measurements at distances between few 100's of metres and several km. The trade-offs between acquisition time, maximum range and excitation laser power levels are discussed and projections made for this and future depth imaging systems. State-of-the-art TCSPC hardware solutions facilitate the rapid transfer and storage of large quantities of raw data. This renders possible real-time analysis with speed-optimised algorithms such as fast Fourier transform-supported cross-correlation methods, as well as gathering additional information about the scene in post-processing steps, based on approaches such as reversible-jump Markov-chain Monte Carlo (RJMCMC). This algorithm dynamically adapts the number of degrees of freedom of a range measurement, resulting in multi-surface resolution and the possible identification of targets obscured by objects such as foliage.

Proceedings Article | 29 April 2009 Paper

Scanning of low-signature targets using time-correlated single-photon counting

G. Buller, R. Collins, N. Krichel, A. Wallace, A. McCarthy

Proceedings Volume 7320, 732003 (2009) https://doi.org/10.1117/12.818645

KEYWORDS: Sensors, Mirrors, Signal to noise ratio, Semiconductor lasers, Pulsed laser operation, Head, Target acquisition, Cameras, Objectives, Target detection

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Showing 5 of 7 publications

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