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9 April 2002 Damage testing of partial reflectors for 157-nm laser calorimeters
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We determined the damage thresholds and lifetimes of several materials using 157- and 193-nm excimer lasers and a beam profile technique similar to that described in ISO 11254-2. We made these measurements to select an appropriate absorbing material for use in our primary standard laser calorimeter for 157-nm excimer laser energy measurements. The materials we tested were nickel-plated sapphire, chemically-vapor-deposited silicon carbide (CVD SiC), nickel-plated copper, and polished copper. Applied pulse energy densities (or dose) ranged from 80 to 840 mJ/cm2. We determined the applied dose from a series of laser beam profile measurements. Silicon carbide had the highest damage threshold: 730 mJ/cm2 per pulse. For this reason, and because of its high thermal and electrical conductivities, we have chosen silicon carbide as the absorber material for the 157-nm calorimeter. We also conducted long-term exposure studies in cooperation with MIT Lincoln Laboratory at a pulse energy density of 5 mJ/cm2 to simulate typical calorimeter operating conditions. No aging effects or other surface changes were observed at these dose levels after 500 million pulses, corresponding to a projected calorimeter lifetime of 50 years.
© (2002) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Holger Laabs, Richard D. Jones, Christopher L. Cromer, Marla L. Dowell, and Vladimir Liberman "Damage testing of partial reflectors for 157-nm laser calorimeters", Proc. SPIE 4679, Laser-Induced Damage in Optical Materials: 2001, (9 April 2002);


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