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Large Area Laser Conditioning of Dielectric Thin Film Mirrors Pages: 17 Published: Jan 1990
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View License Agreement Source: STP1117-EB Abstract The laser conditioning of dielectric thin film HR coatings has been studied as a practical method for the improvement of the damage thresholds of large area (1.1 m dia.) high power 1064 nm laser mirrors on the LLNL 120 kJ, 100 TW Nova laser system. Both HfO2/SiO2 and ZrO2/SiO2HR coatings were conditioned by rastering with a small (∼0.2 mm) diameter beam from a pulsed (18 Hz, 8 ns) Nd-YAG laser (1064 nm). The samples were rastered at various fluences below the unconditioned damage threshold and subsequently damage tested. Large area conditioning studies were also performed using a large aperture beam of the Nova laser. The laser conditioning effect was found to be permanent. Improvements in damage threshold due to conditioning were as high as a factor of 2.7 and were dependent on the conditioning parameters. A model for the conditioning effect is proposed based on the emptying of electronic defect levels within the bandgap of the dielectric materials. Keywords: electronic defects, halfnia, HR coatings, laser conditioning, laser damage, silica, zirconia Paper ID: STP26505S Committee/Subcommittee: E13.15 DOI: 10.1520/STP26505S ASTM International is a member of CrossRef. | ||