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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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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