The application of laser-induced damage spot size effect for laser conditioning mechanism

¹ School of Science, Beijing University of Chemical Technology, 100029, Beijing, P.R. China
² Key Laboratory of High Power Laser Materials, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, P.R. China

^a e-mail: lixiao@mail.buct.edu.cn

Received: 6 December 2011
Revised: 29 May 2012
Accepted: 23 July 2012
Published online: 17 August 2012

Abstract

We propose the spot-size effect in laser-induced damage to optical thin films as a method to investigate the defect removal model which is one of the laser conditioning mechanisms, and the theoretical and experimental studies are presented. A standard deviation σ² is set up for fitting the damage thresholds which are obtained by multi-spot size test. The laser conditioning effect on ZrO₂/SiO₂ multilayer high reflective films is analyzed through this application. It is found that the mean distance of two initiating defects is increased by laser conditioning, which means that the defect density is decreased. Thus, the initiating defects are removed partially by laser conditioning. Furthermore, the intrinsic damage threshold of the film is little affected through the laser conditioning process.