MULTISHOT LASER ALTIMETER - DESIGN AND PERFORMANCE

The maximum measurement range of a laser altimeter can be extended by averaging the measurements from multiple laser shots at the same targe t. We present the principles of operation and design of such a multish ot laser altimeter, which uses a Si avalanche photodiode detector. Aa an example, the performance of a spaceborne multishot altimeter contai ning components similar to those of the single-shot Mars Observer Lase r Altimeter are given under operating conditions that would be encount ered near Saturn. With 100-shot averages, we show that the multishot l aser altimeter is capable of accurate ranging at fly-by distances of 1 0,000 km from an icy satellite. With 100-shot averages, the minimum op tical signal level at a 90% correct-measurement probability under nigh ttime background is 9.8 detected signal photons per pulse as compared with 76 photons per pulse with a single shot.