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Laser Damage on Zinc Selenide and Cadmium Telluride Using the Stanford Mark III Infrared Free Electron Laser

SV. BensonEL. DotteryBA. HooperJMJ MadeyEB. Szarmes

出版	ASTM International, 1988
URL	http://books.google.com.hk/books?id=Pe14zgEACAAJ&hl=&source=gbs_api

註釋We have encountered intracavity optical damage, and have estimated fluence damage thresholds, in samples of CVD zinc selenide which have been used as intracavity Brewster plate output couplers for the Stanford Mark III infrared free electron laser. For spot radii of approximately 1.4 mm and wavelengths in the range of 3 ?n to 4 ?m, we have determined damage thresholds ranging from 8.2 J/cm2 to 11.3 J/cm2 for optical macropulses of 2 ?s duration and 15 Hz repetition rate, with corresponding circulating micropulse intensities on the order of 5 GW/cm2; in most cases catastrophic damage seemed to occur due to the coalescence of tiny pits in the surface. We also report on damage threshold measurements for uncoated cadmium telluride at 3.2 ?m, and observe a fluence dependent damage threshold of approximately 6.3 J/cm2 for macropulses scaled (via ?1/2) to a 1 ?s duration. Finally, we observe a lowering of the damage threshold of uncoated CdTe in the presence of the laser harmonics, presumably due to free carrier absorption of the fundamental.