Catastrophic failure of contaminated fused-silica optics at 355 nm
Abstract
For years, contamination has been known to degrade the performance of optics and to sometimes initiate laser-induced damage to initiate. This study has started to quantify these effects for fused silica windows used at 355 nm. Contamination particles (Al, Cu, TiO2 and ZrO2) were artificially deposited onto the surface and damage tests were conducted with a 3 ns Nd:YAG laser. The damage morphology was characterized by Nomarski optical microscopy. The results showed that the damage morphology for input and output surface contamination is different. For input surface contamination, both input and output surfaces can damage. In particular, the particle can induce pitting or drilling of the surface where the beam exists. Such damage usually grows catastrophically. Output surface contamination is usually ablated away on the first shot but can also induced catastrophic damage. Plasmas are observed during illumination and seem to play an important role in the damage mechanism. The relationship between fluence and contamination size for which catastrophic damage occurred was plotted for different contamination materials. The results show that particles even as small as 10 micrometers can substantially decrease the damage threshold of the window and that metallic particles on the input surface have a more negative effect than oxide particles.
- Publication:
-
Solid State Lasers for Application to Inertial Confinement Fusion: Second Annual International Conference
- Pub Date:
- December 1997
- Bibcode:
- 1997SPIE.3047..987G