Effect of polishing process on silica surface laser-induced damage threshold at 355 nm

In order to obtain optical surfaces of high quality in terms of roughness and cleanness, preparation of silica substrates requires specific processes. Particularly, polishing is one of the most critical stages of these processes. Indeed, fine abrasive liquids are used to reduce cracks induced on the surface by mechanical stress of the previous stages. During the last stages of the process, nano-sized particles used for the abrasion of the surface remain in residual cracks in a thickness of a few micrometers. These contaminants, because of their size and nature, could be suspected to be precursor centers of laser-damage. The purpose of this paper consists in an investigation of the role of particles present in polishing liquids on laser-damage threshold of associated polished surfaces. (C) 2004 Elsevier B.V. All rights reserved.