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

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.

[1]  Pierre Garrec,et al.  Local refusion of silica by a continuous CO2 laser for the mitigation of laser damage growth , 2004, SPIE Optical Systems Design.

[2]  J. Lambropoulos,et al.  Subsurface damage in some single crystalline optical materials. , 2005, Applied optics.

[3]  Gerard Raze,et al.  The impact of laser damage on the lifetime of optical components in fusion lasers , 2004, SPIE Laser Damage.

[4]  Donald Golini,et al.  Effect of Etching and Imaging Mode on the Measurement of Subsurface Damage in Microground Optical Glasses , 1994 .

[5]  Janet B. Davis,et al.  Subsurface Damage in Optical Materials: Origin, Measurement and Removal , 1988, Optical Fabrication and Testing.

[6]  P. Miller,et al.  Sub-surface mechanical damage distributions during grinding of fused silica , 2005 .

[7]  Herve Bercegol,et al.  Fracture related initiation and growth of surface laser damage in fused silica , 2008, Laser Damage.

[8]  Herve Graillot,et al.  The LIL facility quadruplet commissioning , 2006 .

[9]  I. Iordanoff,et al.  A discrete element model to investigate sub-surface damage due to surface polishing , 2008 .

[10]  Michael D. Feit,et al.  Methods for mitigating surface damage growth in NIF final optics , 2002, SPIE Laser Damage.

[11]  Wiktor J. Rupp,et al.  Mechanism of the Diamond Lapping Process , 1974 .

[12]  Michel L. Andre,et al.  Status of the LMJ project , 1997, Other Conferences.

[13]  Stavros G Demos,et al.  Investigation of processes leading to damage growth in optical materials for large-aperture lasers. , 2002, Applied optics.

[14]  J. Néauport,et al.  Polishing-induced contamination of fused silica optics and laser induced damage density at 351 nm. , 2005, Optics express.