Optimizing fused silica polishing processes for 351nm high-power laser application

Abstract

During the development of the laser megajoule (LMJ), a high power laser facility dedicated to DT fusion, CEA has made important efforts to understand and improve laser induced damage threshold of fused silica optics at the wavelength of 351 nm. For several years, with various industrials and academics partners, we have focused on optimizing the grinding, lapping and polishing processes to increase materials performance. In this paper, we describe our efforts in various fields: subsurface damage characterization, lapping process simulation, diamond grinding and lapping machine instrumentations, ... Our concern is to control and manage the material removal at each step of the process in order to reduce the cracks region extension and thus to diminish the damage density.