A low-noise laser-gated imaging system for long-range target identification

Ian M. Baker; Stuart S. Duncan; Jeremy W. Copley

doi:10.1117/12.541484

30 August 2004 A low-noise laser-gated imaging system for long-range target identification

Ian M. Baker, Stuart S. Duncan, Jeremy W. Copley

Proceedings Volume 5406, Infrared Technology and Applications XXX; (2004) https://doi.org/10.1117/12.541484
Event: Defense and Security, 2004, Orlando, Florida, United States

Abstract

BAE SYSTEMS has developed a laser-illuminated, gated imaging system for long range target identification which has generated bright images at ranges in excess of 10km from modest laser energies. The system is based on a short pulsewidth laser and a custom detector for sensing the return pulse. The source is a Nd YAG laser converted by an optical parametric oscillator (OPO) to 1571nm and producing 20ns pulses at 15Hz. The detector (named SWIFT) is a 320x256 array of HgCdTe photodiodes operating with high avalanche gain to achieve sensitivities as low as 10 photon rms. A custom silicon multiplexer performs the signal injection and temporal gating function, and adds additional electronic gain. Trials show that the current detectors have gate edges equivalent to 1.5m in range and complete extinction of signals outside of the gated range. The detector is encapsulated in an integrated-detector-cooler-assembly and utilises standard productionised thermal imaging electronics to perform non-uniformity correction and grey scale images. Imaging trials using the camera have shown little excess noise, crosstalk or non-uniformity due to the use of avalanching in the HgCdTe photodiodes up to gains of over 100. The images have shown high spatial resolution arising from the use of solid state focal plane array technology. The imagery, collected both in the laboratory and in field trials, has been used to explore the phenomenology unique to laser-illuminated targets and to verify system models.

Citation Download Citation

Ian M. Baker, Stuart S. Duncan, and Jeremy W. Copley "A low-noise laser-gated imaging system for long-range target identification", Proc. SPIE 5406, Infrared Technology and Applications XXX, (30 August 2004); https://doi.org/10.1117/12.541484

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