Measurement and Identification of Laser-Damage Thresholds in Thin Films

摘要

The source and magnitude of uncertainties in the measurement of practical laser-damage thresholds are discussed. Damage is defined to be a permanent induced change in a bare or coated optical surface which degrades the merit of the surface with regard to specifications such as scattering, reflection, or transmission. Bulk damage is not treated, and the discussion is limited to tests conducted with laser pulses having wavelengths of 694 nm or 1064 nm and durations less than 100 ns. The measurement of pulse energy, the spatial and temporal profile of the pulse, and determination of the occurrence of damage are described in detail. It is shown that the uncertainty in the measurement of absolute laser-damage thresholds can be as small as 10% and that, within such limits, there is no site-to-site variation of the threshold of optical surfaces. (ERA citation 03:048412)