SEDL / STP / STP911-EB / STP28978S

Measurements of the Dependence of Damage Thresholds on Laser Wavelength, Pulse Duration and Film Thickness

Rainer, F
Lawrence Livermore National Laboratory, Livermore, CA

Vercimak, CL
Lawrence Livermore National Laboratory, Livermore, CA

Milam, D
Lawrence Livermore National Laboratory, Livermore, CA

Carniglia, CK
Lawrence Livermore National Laboratory, Livermore, CA

Hart, TT
Lawrence Livermore National Laboratory, Livermore, CA

Pages: 9    Published: Jan 1985

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Abstract

Results of three experiments will be described. We used 351-nm and 355-nm pulses with durations of 0.6, 1, 5 and 9 ns to measure thresholds for a variety of anti-reflectance and high reflectance coatings. The functional form t^m, with t the pulse duration, was used to scale fluence thresholds measured at 0.6 ns to those measured at 9.0 ns. Values of the coefficient m ranged from 0.10 to 0.51. The average value was 0.30. In the second experiment, we measured thresholds at 1064 nm, 527 nm and 355 nm for single-frequency high reflectance ZrO²/SiO² coatings. Coatings for all three frequencies were deposited simultaneously by use of masks in the coating chamber. Thresholds varied from 2–4 J/cm² at 355 nm to 7–10 J/cm² at 1064 nm. The third experiment measured thresholds at 355 nm for antireflection coatings made with layer thicknesses varying from greater than one wavelength to less than a quarterwavelength. A significant variation of threshold with coating thickness was not observed, but the median thresholds increased slightly as coating thickness increased.