Influence of deposition parameters on laser-damage threshold of silica-tantala AR coatings
A series of 4-layer silica-tantala antireflection coatings was deposited under 18 different combinations of substrate temperature (175, 250, and 325 /sup 0/C), oxygen pressure (0.5, 1.0, and 2.0 x 10/sup -4/ Torr), and rate of deposition (1.5 and 5 A/sec). Measurements of laser-damage threshold for 1064-nm, 1-nsec pulses, average absorption, net stress, and reflectivity were then made on these coatings. Coatings deposited at the lowest temperature had the highest damage thresholds. Damage thresholds were found not to be directly related to average absorption or net stress. Coatings deposited on fused silica substrates which had been polished by a bowl-feed process had generally higher damage thresholds than coatings deposited on conventionally polished fused silica or on BK-7 glass polished by either conventional or bowl-feed processes. Baking coatings in air for 4 h at 400 /sup 0/C generally reduced average absorption and net stress, changed the net stress from compression to tension and, in some cases, increased the damage threshold.
- Research Organization:
- C. K. Carniglia and T. T. Hart are with Optical Coating Laboratory, Inc., P. O. Box 1599, Santa Rosa, California 95403; the other authors are with University of California, Lawrence Livermore National Laboratory, P.O. Box 5508, Livermore, California 94550.
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5710168
- Journal Information:
- Appl. Opt.; (United States), Journal Name: Appl. Opt.; (United States) Vol. 21:20; ISSN APOPA
- Country of Publication:
- United States
- Language:
- English
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360204 -- Ceramics
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42 ENGINEERING
420300 -- Engineering-- Lasers-- (-1989)
ANTIREFLECTION COATINGS
CHALCOGENIDES
COATINGS
DAMAGE
DEPOSITION
LASER MATERIALS
MATERIALS
MINERALS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PRESSURE DEPENDENCE
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SUBSTRATES
TANTALUM COMPOUNDS
TANTALUM OXIDES
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPOUNDS