Dependence of Pulsed Laser-Induced Damage to Optical Surfaces on the Species and Pressure of an Ambient Gas

摘要

The testing of optical materials in electronegative gases was investigated to determine if an increase in the resistance of the material to pulsed laser-induced damage could be realized as indicated by the Soviet literature. The materials were irradiated with a 1.06 micrometer laser pulse of 5 nsec and a spot size (1/e squared-radius) of 148 micrometer. The materials used for testing consisted of zirconium oxide dielectric thin films (lambda/2 at 1.06 micrometer), copper mirrors, fused silica substrates, Hoya's ARG-2 Glass, and porous sol-gel drived coatings. Each material was tested in environments of nitrogen tetrafluoromethane and sulfur hexafluoride for pressures ranging from less than 10 to the minus 5th power torr to 600 torr. The results indicated that the energy density damage was unaffected by the type or pressure of the gas surrounding the material for single shot damage testing.