SEDL / STP / STP1015-EB / STP18780S

Thresholds Measured With 350-nm Pulses at 25–100 Hz for Bare Polished Crystals of CaF² and for Silica Sol-gel AR Coatings on Silica Substrates

Staggs, MC
Lawrence Livermore National Laboratory University of California, Livermore,California

Milam, D
Lawrence Livermore National Laboratory University of California, Livermore,California

Thomas, IM
Lawrence Livermore National Laboratory University of California, Livermore,California

Wilder, JG
Lawrence Livermore National Laboratory University of California, Livermore,California

Pages: 8    Published: Jan 1988

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Source: STP1015-EB

Abstract

An XeF laser-damage experiment was used to measure damage thresholds for bare polished crystals of CaF² and porous silica antireflection coatings on fused silica substrates. Damage was induced by applying 1000 350-nm, 25-ns pulses at repetition rates of 25–100 Hz to small (typically 0.12 × .03 cm) sites on the surfaces of the sample. Eight samples of fluorescence-free CaF² exhibited both surface and bulk damage at fluences as low as 10 J/cm². Three samples of UV-grade CaF² also had surface damage thresholds of 10 J/cm², and bulk damage was not observed in this material. Thresholds for the porous silica coatings were 17–23 J/cm².

Keywords:
calcium fluoride, multishot damage testing, porous silica antireflection coatings, ultraviolet laser damage

Paper ID: STP18780S
Committee/Subcommittee: F01.11
DOI: 10.1520/STP18780S
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