SEDL / STP / STP799-EB / STP37230S

Laser Damage Measurements at 492 nm Using a Flashlamp-Pumped Dye Laser

Marrs, CD
Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, California

Faith, WN
Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, California

Dancy, JH
Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, California

Porteus, JO
Michelson Laboratory, Physics Division Naval Weapons Center, China Lake, California

Pages: 9    Published: Jan 1983

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Abstract

A triaxial flashlamp-pumped dye laser has been developed into a characterizable source for laser damage studies. The temperature of the dye is maintained constant to ±0.2°C via three heat exchangers and flow regulation of the dye, coolant, and refrigerant. Using LD 490 laser dye and maintaining a temperature of 1.1 ± 0.2°C cooler than the temperature of the coolant, the laser produces 0.18 J, 0.5 μsec pulses at 492 nm. The pulse-to-pulse energy stability is ±3%. The spatial profile of the focused beam was measured in orthogonal directions in the plane of damage of the focus lens. The orthogonal profiles were flat-topped Gaussians with 1/e² widths of 270 μm. Laser damage measurements have been performed at 492 nm on high reflectance dielectric mirrors, and no correlation was found between the reflectance or total integrated scatter and the axial fluence at which damage was observed. The damage morphology observed on the dielectric mirrors was dominated by failure of the coatings at defects (selective damage sites). In addition, multithreshold laser damage measurements were performed on polished bulk Mo and on the following diamond-turned metals: bulk Al alloy, bulk Cu, electrodeposited Ag, and electrodeposited Au. Comparisons are made between calculated and experimentally measured slip and melt thresholds.