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Proceedings Paper

Second generation airborne 3D imaging lidars based on photon counting
Author(s): John Degnan; David Wells; Roman Machan; Ed Leventhal
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Paper Abstract

The first successful photon-counting airborne laser altimeter was demonstrated in 2001 under NASA's Instrument Incubator Program (IIP). This "micro-altimeter" flew at altitudes up to 22,000 ft (6.7 km) and, using single photon returns in daylight, successfully recorded high resolution images of the underlying topography including soil, low-lying vegetation, tree canopies, water surfaces, man-made structures, ocean waves, and moving vehicles. The lidar, which operated at a wavelength of 532 nm near the peak of the solar irradiance curve, was also able to see the underlying terrain through trees and thick atmospheric haze and performed shallow water bathymetry to depths of a few meters over the Atlantic Ocean and Assawoman Bay off the Virginia coast. Sigma Space Corporation has recently developed second generation systems suitable for use in a small aircraft or mini UAV. A frequency-doubled Nd:YAG microchip laser generates few microjoule, subnanosecond pulses at fire rates up to 22 kHz. A Diffractive Optical Element (DOE) breaks the transmit beam into a 10x10 array of quasi-uniform spots which are imaged by the receive optics onto individual anodes of a high efficiency 10x10 GaAsP segmented anode microchannel plate photomultiplier. Each anode is input to one channel of a 100 channel, multistop timer demonstrated to have a 100 picosecond timing (1.5 cm range) resolution and an event recovery time less than 2 nsec. The pattern and frequency of a dual wedge optical scanner, synchronized to the laser fire rate, are tailored to provide contiguous coverage of a ground scene in a single overflight.

Paper Details

Date Published: 15 October 2007
PDF: 7 pages
Proc. SPIE 6771, Advanced Photon Counting Techniques II, 67710N (15 October 2007); doi: 10.1117/12.732086
Show Author Affiliations
John Degnan, Sigma Space Corp. (United States)
David Wells, Sigma Space Corp. (United States)
Roman Machan, Sigma Space Corp. (United States)
Ed Leventhal, Sigma Space Corp. (United States)

Published in SPIE Proceedings Vol. 6771:
Advanced Photon Counting Techniques II
Wolfgang Becker, Editor(s)

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