30 May 2003 Influence of 527-nm laser light on debris- and shrapnel-contaminated optical surfaces
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The use of large aperture high power lasers to study plasmas formed from solid targets is well known. In this paper we consider the effects of second harmonic Neodymium laser radiation [527 nm] on optical surfaces that have been contaminated by solid shrapnel and liquid or gaseous debris arising from the use of laser irradiated solid targets. In typical operations large lasers use debris shields to protect expensive aspheric lenses from optical and mechanical damage. These debris shields have a finite lifetime before they need to be replaced. Criteria for replacement have often been derived empirically from operational experience of evacuated target chambers and may be based on transmission, reflectivity, scatter or obscuration measurements. Here we describe and characterize the debris produced from targets based on gas bags, spall packages and gold halfraums captured on fused silica borosilicate plates. The influence of contamination levels and the physical form of debris on laser beams of various fluences was measured. Laser cleaning, damage thresholds and growth rates were investigated and the techniques are described.
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James E. Andrew, Karen R. Mann, Michael T. Tobin, Joe C. Watson, "Influence of 527-nm laser light on debris- and shrapnel-contaminated optical surfaces", Proc. SPIE 4932, Laser-Induced Damage in Optical Materials: 2002 and 7th International Workshop on Laser Beam and Optics Characterization, (30 May 2003); doi: 10.1117/12.472056; https://doi.org/10.1117/12.472056

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