Gerald S. Buller

Heriot-Watt University, Edinburgh, Scotland, United Kingdom

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Publications (164)247.25 Total impact

  • Nils J Krichel, Aongus McCarthy, Gerald S Buller
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    ABSTRACT: Time-correlated single-photon counting techniques have recently been used in ranging and depth imaging systems that are based on time-of-flight measurements. These systems transmit low average power pulsed laser signals and measure the scattered return photons. The use of periodic laser pulses means that absolute ranges can only be measured unambiguously at low repetition rates (typically <100 kHz for > 1 km) to ensure that only one pulse is in transit at any instant. We demonstrate the application of a pseudo-random pattern matching technique to a scanning rangefinder system using GHz base clock rates, permitting the acquisition of unambiguous, three-dimensional images at average pulse rates equivalent to >10 MHz. Depth images with centimeter distance uncertainty at ranges between 50 m and 4.4 km are presented.
    Optics Express 04/2010; 18(9):9192-206. · 3.55 Impact Factor
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    ABSTRACT: Single-photon detection technologies in conjunction with low laser illumination powers allow for the eye-safe acquisition of time-of-flight range information on non-cooperative target surfaces. We previously presented a photon-counting depth imaging system designed for the rapid acquisition of three-dimensional target models by steering a single scanning pixel across the field angle of interest. To minimise the per-pixel dwelling times required to obtain sufficient photon statistics for accurate distance resolution, periodic illumination at multi- MHz repetition rates was applied. Modern time-correlated single-photon counting (TCSPC) hardware allowed for depth measurements with sub-mm precision. Resolving the absolute target range with a fast periodic signal is only possible at sufficiently short distances: if the round-trip time towards an object is extended beyond the timespan between two trigger pulses, the return signal cannot be assigned to an unambiguous range value. Whereas constructing a precise depth image based on relative results may still be possible, problems emerge for large or unknown pixel-by-pixel separations or in applications with a wide range of possible scene distances. We introduce a technique to avoid range ambiguity effects in time-of-flight depth imaging systems at high average pulse rates. A long pseudo-random bitstream is used to trigger the illuminating laser. A cyclic, fast-Fourier supported analysis algorithm is used to search for the pattern within return photon events. We demonstrate this approach at base clock rates of up to 2 GHz with varying pattern lengths, allowing for unambiguous distances of several kilometers. Scans at long stand-off distances and of scenes with large pixel-to-pixel range differences are presented. Numerical simulations are performed to investigate the relative merits of the technique.
    Proc SPIE 04/2010;
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    ABSTRACT: Single-photon sources and detectors are key enabling technologies for photonics in quantum information science and technology (QIST). QIST applications place high-level demands on the performance of sources and detectors; it is therefore essential that their properties can be characterized accurately. Superconducting nanowire single-photon detectors (SNSPDs) have spectral sensitivity from visible to beyond 2 mum in wavelength, picosecond timing resolution (Jitter
    Proc SPIE 04/2010;
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    ABSTRACT: In recent years, time-correlated single-photon counting techniques have been applied to time-of-flight measurements for long-distance range-finding and depth imaging. Depth imaging has been performed by obtaining timing information from an individual single-photon detector and scanning the optical field to obtain a full depth image. Typically, the measurement is made by dwelling on each individual depth pixel for a pre-defined integration time and completing the data acquisition for that pixel before steering the beam to the adjacent spatial position. We present a novel photon-counting data acquisition mode where the time-of-flight histograms for each depth pixel are gradually populated. The system repeatedly scans the same spatial frame with short per-pixel dwell times, and sufficient photon statistics are built up over many frames by cumulating photon events from all acquired frames. The technique is used to compare the depth imaging performance of two single-photon avalanche diode detectors: a novel, resonant-cavity enhanced shallow-junction device; and a commercially available thick-junction device.
    Journal of Modern Optics 02/2010; 58(3-4-58):244-256. · 1.16 Impact Factor
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    ABSTRACT: The new generation of 3D imaging systems based on laser radar (ladar) offers significant advantages in defense and security applications. In particular, it is possible to retrieve 3D shape information directly from the scene and separate a target from background or foreground clutter by extracting a narrow depth range from the field of view by range gating, either in the sensor or by postprocessing. We discuss and demonstrate the applicability of full-waveform ladar to produce multilayer 3D imagery, in which each pixel produces a complex temporal response that describes the scene structure. Such complexity caused bymultiple and distributed reflection arises inmany relevant scenarios, for example in viewing partially occluded targets, through semitransparent materials (e.g., windows) and through distributed reflective media such as foliage. We demonstrate our methodology on 3D image data acquired by a scanning time-of-flight system, developed in our own laboratories, which uses the time-correlated single-photon counting technique.
    EURASIP Journal on Advances in Signal Processing 01/2010; 2010:33. · 0.89 Impact Factor
  • G. S. Buller, N. J. Krichel, A. McCarthy
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    ABSTRACT: This paper describes progress on low optical power LIDAR and depth imaging systems using pulsed semiconductor laser diodes and time-correlated single-photon counting.
    01/2010;
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    G S Buller, R J Collins
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    ABSTRACT: The detection and generation of single photons has seen an upsurge in interest in recent years as new scientific fields of research, for example quantum information processing, have been established. This review serves to provide an overview of progress in these areas, describing some of the main candidates for single-photon components for use in emerging fields of research.
    Measurement Science and Technology 01/2010; 21:12002-28. · 1.44 Impact Factor
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    ABSTRACT: not available.
    Journal of Nanophotonics. 01/2010; 4(1).
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    Robert Lamb, Gerald Buller
    Spie Newsroom. 01/2010;
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    ABSTRACT: We describe a scanning time-of-flight system which uses the time-correlated single-photon counting technique to produce three-dimensional depth images of distant, noncooperative surfaces when these targets are illuminated by a kHz to MHz repetition rate pulsed laser source. The data for the scene are acquired using a scanning optical system and an individual single-photon detector. Depth images have been successfully acquired with centimeter xyz resolution, in daylight conditions, for low-signature targets in field trials at distances of up to 325 m using an output illumination with an average optical power of less than 50 microW.
    Applied Optics 11/2009; 48(32):6241-51. · 1.69 Impact Factor
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    R.E. Warburton, M.A. Itzler, G.S. Buller
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    ABSTRACT: Room-temperature operation of InGaAs/InP single-photon avalanche diode detectors operating in free-running mode, with no electrical gating, is demonstrated. An improved design of device structure permitted significantly lower dark count rates than previously reported. Free-running operation at room temperature using an incident wavelength of 1550 nm gave a noise equivalent power of 1.5 10<sup>-15</sup> WHz<sup>-1/2</sup> with improved photon timing jitter.
    Electronics Letters 10/2009; · 1.04 Impact Factor
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    ABSTRACT: We describe a scanning time-of-flight system which uses the time-correlated single photon-counting technique to produce three-dimensional depth images of scenes using low average laser power levels (ie
    Proc SPIE 05/2009;
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    Ryan E. Warburton, Mark Itzler, Gerald S. Buller
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    ABSTRACT: Passive quenching operation of an InGaAs/InP single-photon avalanche diode detector at low excess bias is reported in terms of the key figures of merit including afterpulsing analysis. The reduced charge required to measure individual photon events meant that room temperature single-photon counting at 1550 nm wavelength was achievable without the requirement of electrical gating and with negligible afterpulsing effects evident.
    Applied Physics Letters 02/2009; 94(7). · 3.79 Impact Factor
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    ABSTRACT: This paper describes progress in gigahertz-clocked quantum key distribution systems. It details current advances in both point-to-point and network applications.
    01/2009;
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    Spie Newsroom. 01/2009;
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    ABSTRACT: Single-photon detectors are a key enabling technology for optical quantum information processing applications such as quantum key distribution. A new class of single-photon detectors have emerged based on superconducting nanowires. These detectors offer sensitivity at telecommunication wavelengths (1310nm and 1550nm) with low dark counts and excellent timing resolution at an operating temperature of ~4 K. We have integrated four independent fibre-coupled detectors into a practical closed-cycle refrigerator and plan to employ this multichannel detector system in advanced quantum information processing experiments.
    Quantum Communication and Quantum Networking, First International Conference, QuantumComm 2009, Naples, Italy, October 26-30, 2009, Revised Selected Papers; 01/2009
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    ABSTRACT: We study the Fourier relationship between angular position and orbital angular momentum of entangled photons. We establish that the amplitudes of the angular position and the orbital angular momentum distributions are related as conjugate Fourier-pairs.
    Laser Science; 10/2008
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    ABSTRACT: We study the Fourier relationship between angle and orbital angular momentum of entangled photons. Spatial light modulators allow us to define and control the spatial mode measurement state. We observe strong quantum correlations, establishing that angular position and momentum distributions between the photons are related as conjugate Fourier pairs.
    Physical Review A 10/2008; 78(4):043810. · 3.04 Impact Factor
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    ABSTRACT: This paper describes a rapid data acquisition photon-counting time-of-flight ranging technique that is designed for the avoidance of range ambiguity, an issue commonly found in high repetition frequency time-off-light systems. The technique transmits a non-periodic pulse train based on the random bin filling of a high frequency time clock. A received pattern is formed from the arrival times of the returning single photons and the correlation between the transmitted and received patterns was used to identify the unique target time-of-flight. The paper describes experiments in laboratory and in free space at over several hundred meters range at clock frequencies of 1GHz. Unambiguous photon-counting range-finding is demonstrated with centimeter accuracy.
    Optics Express 10/2008; 16(18):13685-98. · 3.55 Impact Factor
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    ABSTRACT: Time-correlated single-photon counting techniques using individual optimized detectors have been applied to time-of-flight ranging and depth imaging. This paper describes recent progress in photon-counting systems performing surface mapping of non-cooperative targets. This includes systems designed for short ranges of the order of 1-50 meters, and longer ranges of up to ten kilometers. The technique has also been applied to distributed surfaces. We describe the measurement approach, techniques used for scanning, as well as the signal analysis methodology and algorithm selection. The technique is fundamentally flexible: the trade-off between the integrated number of counts (or acquisition time) against range repeatability or depth resolution allows its application in a number of diverse fields. The inherent time gating of the technique, allied to the spatial filtering provided by small active area single-photon detectors, can lead to operation under high ambient light conditions even with low average optical power pulsed sources. We have demonstrated three-dimensional imaging of meter-dimensioned objects where reverse engineering methods using cooperative targets cannot be routinely employed: e.g. delicate objects, or objects with more than one reflective surface. Using more advanced signal processing algorithms, we have been able to improve the system performance significantly, as measured by the depth resolution at short and long ranges. Furthermore, the application of these methodologies has allowed us to characterize the positions and amplitudes of multiple returns. Hence, the approach can be used for characterization of distributed non-cooperative targets at kilometer ranges, even in environments where low-light level and and/or eye-safe operation is necessary. The technique has also been applied in conjunction with a rapid scanning approach, to acquire three-dimensional information of a target scene with frame times of approximately 1 second.
    Proc SPIE 01/2008;

Publication Stats

992 Citations
247.25 Total Impact Points

Institutions

  • 1989–2014
    • Heriot-Watt University
      • • Institute of Photonics and Quantum Sciences (IPaQS)
      • • School of Engineering and Physical Sciences
      • • Department of Electrical, Electronic and Computer Engineering
      • • Department of Physics
      Edinburgh, Scotland, United Kingdom
  • 2012
    • University of Glasgow
      • School of Physics and Astronomy
      Glasgow, SCT, United Kingdom
  • 2000
    • Politecnico di Milano
      Milano, Lombardy, Italy