Fabrication of laser mirrors using ion beam sputter deposition

Abstract

The problems of laser damage in thin film laser mirrors is widely reported and techniques to increase laser induced damage threshold are continually being sought. This paper describes the design and manufacture of laser mirrors for high power lasers using ion beam sputter deposition techniques in a production sized box coater. Substrate preparation is described, the use of evaluation techniques to assess quality are discussed and the problems to be solved with ion beam processes are highlighted. Laser mirrors with extremely low losses (a few parts per million) have been fabricated and the laser induced damage threshold measured using high power ruby and YAG lasers. This is compared with similarly designed laser mirrors fabricated by conventional electron beam evaporation and ion assisted deposition, and the results are presented.