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Proceedings Paper

Advanced multifunctional detectors for laser-gated imaging applications
Author(s): Ian Baker; Peter Thorne; James Henderson; Jeremy Copley; David Humphreys; Alasdair Millar
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Paper Abstract

The rapid pace of development in the field of long-range imaging is illustrated by two new detector technologies for passive and active imaging. Active systems, using a near-infrared pulse laser and a fast, gated detector, are now adopted for most long range imaging applications. This concept is often called burst-illumination LIDAR or BIL. The SELEX solid state detector is based on two major components: an array of HgCdTe avalanche photodiodes, and a custom-designed CMOS multiplexer to perform the fast gating and photon signal capture. These hybrid arrays produce sensitivities as low as 10 photons rms, due largely to very high, almost noise-free avalanche gain in the HgCdTe diodes. The sensitivity, dynamic range and image quality is now such that the camera performance is usually limited by coherence and scintillation effects in the scene. With this strong sensor capability, it has been possible to launch the next generation of multiplexers to satisfy systems of the future. For instance, most laser-gated imaging systems use a suite of passive infrared and visible cameras to complement the BIL channel. It is highly advantageous to combine these functions into one electro-optic system, leading to a simpler, smaller, lower power and lower cost system. The key technical steps are to find solutions for the difficult multifunctional detector and the dual-wavelength optic. A detector has been developed to image passively in the medium and short wavebands, and actively in BIL mode. The performance of the detector and optic is described. Another major systems enhancement is to be able to generate 3D images, particularly in complex scenes, to further improve background clutter rejection and provide agile, feedback control of the range gating in a dynamic environment. Here the detector senses the range, as well as the laser pulse intensity, on a pixel-by-pixel basis, providing depth context for each laser pulse. A prototype detector has been successfully demonstrated and shown to provide good quality 2D and 3D data for each laser pulse.

Paper Details

Date Published: 17 May 2006
PDF: 10 pages
Proc. SPIE 6206, Infrared Technology and Applications XXXII, 620608 (17 May 2006); doi: 10.1117/12.673577
Show Author Affiliations
Ian Baker, SELEX Sensors and Airborne Systems Infra-Red Ltd. (United Kingdom)
Peter Thorne, SELEX Sensors and Airborne Systems Infra-Red Ltd. (United Kingdom)
James Henderson, SELEX Sensors and Airborne Systems Ltd. (United Kingdom)
Jeremy Copley, SELEX Sensors and Airborne Systems Ltd. (United Kingdom)
David Humphreys, SELEX Sensors and Airborne Systems Ltd. (United Kingdom)
Alasdair Millar, SELEX Sensors and Airborne Systems Ltd. (United Kingdom)

Published in SPIE Proceedings Vol. 6206:
Infrared Technology and Applications XXXII
Bjørn F. Andresen; Gabor F. Fulop; Paul R. Norton, Editor(s)

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