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In this paper we present the results of bulk damage experiments done on Type-IT DKDP triple harmonic generator crystals that were raster conditioned with 35 1-355 urn wavelengths and pulse durations of 4 and 23.2 ns. In the first phase of experiments 20 different scan protocols were rastered into a sample of rapid growth DKDP. The sample was then rastered at damage-causing fluences to determine the three most effective protocols. These three protocols were scanned into a 1 5-cm sample of conventional-growth DKDP and then exposed to single shots of a 1-cm beam from LLNL's Optical Sciences Laser at fluences ranging from 0.5 -1.5X of the 10% damage probability fluence and nominal pulse durations of 0.1, 0.3, 0.8, 3.2, 7.0 and 20 ns. The experiment showed that pulse durations in the 1-3 ns range were much more effective at conditioning than pulses in the 1 6.3 ns range and that the multiple pass "peak fluence" scan was more effective than the single pass "leading edge" scan for 23.2 ns XeF scans.

An experimental technique has been utilized to measure the variation of bulk damage scatter with damaging fluence in plates of KH 2 PO 4 (KDP) crystals. Bulk damage in unconditioned and laser-conditioned doubler-cut KDP crystals has been studied using 527 nm (2ω) light at pulselengths of 0.3 -10 ns. It is found that there is less scatter due to damage at fixed fluence for longer pulselengths. In particular, there is~4X increase in fluence for equivalent scatter for damage at 2ω, 10 ns as compared to 0.30 ns in unconditioned KDP. The results for the unconditioned and conditioned KDP show that for all the pulselengths the scatter due to the bulk damage is a strong function of the damaging fluence (φ~5). It is determined that the 2ω fluence pulselength-scaling for equivalent bulk damage scatter in unconditioned KDP varies as τ 0.30±0.11 and in 3ω, 3ns ramp-conditioned KDP varies as τ 0.27±0.14 . The effectiveness of 2ω and 3ω laser conditioning at pulselengths in the range of 0.30-23 ns for damage induced 2ω, 3 ns is analyzed in terms of scatter. For the protocols tested (i.e. peak conditioning irradiance, etc.), the 3ω, 300 ps conditioning to a peak fluence of 3 J/cm 2 had the best performance under 2ω, 3 ns testing. The general trend in the performance of the conditioning protocols was shorter wavelength and shorter pulselength appear to produce better conditioning for testing at 2ω, 3 ns.

This work is an experimental investigation to evaluate the potential of fluorescence microscopy as a tool to detect surface contamination as well as reveal surface damage precursors on DKDP and S102 optics. To achieve these technical objectives, microscopic imaging systems were built that also incorporated in-situ damage testing capabilities. Fluorescence imaging experiments were performed using 3 5 1 -nm laser excitation while damage testing was performed at relatively high laser fluences. The experimental results demonstrated the potential of this technique to address the aforementioned technical issues.