Proceedings Article | 14 July 1995
Proc. SPIE. 2428, Laser-Induced Damage in Optical Materials: 1994
KEYWORDS: Transmitters, Optical components, Q switching, Laser development, Nd:YAG lasers, Optical coatings, Semiconductor lasers, Laser damage threshold, Q switched lasers, Optical damage
The Geoscience Laser Altimeter System (GLAS) is being developed by NASA/GSFC to measure the dynamics of the ice sheet mass balance, land, cloud, and atmospheric properties. An instrument altimetric resolution of 10 cm per shot is required. The laser transmitter will be a diode-pumped, Q-switched, Nd:YAG laser producing 1064 nm, 100 mJ, 4 ns pulses at 40 Hz repetition rate in a TEM(infinity) mode. A minimum lifetime goal of 2 billion shots is required per laser transmitter. The performance of the GLAS laser can be limited by physical damage to the optical components caused by the interaction of intense laser energy with the optical coatings and substrates. Very little data exists describing the effects of long duration laser exposure, of 4 ns pulses, on an optical component. An Accelerated GLAS Exposure Station (AGES) is being developed which will autonomously operate and monitor the GLAS laser at an accelerated rate of 500 Hz. The effects of a large number of laser shots will be recorded. Parameters to be monitored include: laser power, pulsewidth, beam size, laser diode drive current and power, Q-switch drive voltage, temperature, and humidity. For comparison, one set of AGES sister optical components will be used in the nonaccelerated GLAS laser and another will be evaluated by a commercial optical damage test facility.