| Popis: |
An XeF laser-damage experiment was used to measure damage thresholds for bare polished crystals of CaF/sub 2/ 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 to 100 Hz to small (typically 0.12 x .03 cm) sites on the surfaces of the sample. Eight samples of fluorescence-free CaF/sub 2/ exhibited both surface and bulk damage at fluences as low as 10 J/cm/sup 2/. Three samples of UV-grade CaF/sub 2/ also had surface damage thresholds of 10 J/cm/sup 2/, and bulk damage was not observed in this material. Thresholds for the porous silica coatings were 17 to 23 J/cm/sup 2/. |
