Improved laser-damage-resistant polymethyl methacrylate

The effects of moderate monomer purification before polymerization on the bulk laser-damage properties of polymethyl methacrylate were studied with 1.06-μm-wavelength, 8-nsec-FWHM, 33-μm spot-radius pulses from a Q-switched Nd:YAG laser. The results show that monomer purification can more than double the single-shot damage threshold and significantly raise the one-pulse-per-second low-level multiple-shot damage asymptote of the material. Scattered, depolarized helium–neon laser light and certain characteristics of the single- and multipleshot data strongly suggest that removal of micrometer-sized dust is the primary cause of the improved damage resistance in the purified material.