A Study of FEL-Induced Changes in Mirror Surface Roughness

Alice Ohlson

2004-2005

Abstract

Two pairs of laser cavity mirrors were examined to determine if cosmetic surface flaws were exacerbated by exposure to high-power laser light. Of each pair, one had been used as the high reflector mirror in the optical cavity of the IR-Demo free-electron laser (FEL) at the Thomas Jefferson National Accelerator Facility and exposed to the intracavity laser beam, while the other had not. This study found that the irradiance incident on the ZnSe high reflector during 6um lasing did not cause damage to the optic and consequently did not degrade the laser output. However, the irradiance incident on the 1.064um Sapphire high reflector was great enough to damage it but apparently did not result in a degradation of laser output capabilities.