Effect of laser irradiation on silica substrate contaminated by aluminum particles.

A major issue in the use of high-power lasers, such as the Laser Megajoule (LMJ), is laser-induced damage of optical components. One potential damage initiator is particulate contamination, but its effect is hard to distinguish from that of other damage precursors. To do so, we introduced artificial contaminants typical of metallic pollution likely to be present on the optical components of the LMJ chains. More precisely, aluminum particles of two different sizes were placed on a silica sample. These dots were characterized by optical microscopy and profilometry. Then they were exposed to a laser beam with a pulse length of 6.5 ns at 1064 nm and fluences in the range from 1 to 40 J/cm(2). Each dot was characterized again with the same techniques and also by photothermal microscopy. To complete the experimental results, we performed numerical simulations with a one-dimensional Lagrangian hydrodynamics code. We show that the particle removal by laser irradiation produces a modification of the silica surface that does not evolve into catastrophic damage under subsequent irradiation. However, the effect does depend on the size of the dots. We demonstrate that a procedure exists that removes the dot and leaves the site capable of resisting high fluence.

[1]  F. Y. Llnl Genin.  Catastrophic failure of contaminated fused silica optics at 355 nm , 1996 .

[2]  B. Martinez,et al.  Numerical and experimental study of focal spot degragation induced by particles on surface optics , 2007, SPIE Laser Damage.

[3]  Nastaran Mansour,et al.  Laser-Induced Damage And The Role Of Self-Focusing , 1989 .

[4]  D Milam,et al.  Nonlinear formation of holographic images of obscurations in laser beams. , 1997, Applied optics.

[5]  Patrick Combis,et al.  Laser-induced damage simulations of absorbing materials under pulsed IR irradiation , 2000, Laser Damage.

[6]  N. Bloembergen.  Role of cracks, pores, and absorbing inclusions on laser induced damage threshold at surfaces of transparent dielectrics. , 1973, Applied optics.

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

[8]  Mireille Commandré,et al.  High-resolution photothermal microscope: a sensitive tool for the detection of isolated absorbing defects in optical coatings. , 2006, Applied optics.

[9]  Deborah M. Kane,et al.  Reduced threshold ultraviolet laser ablation of glass substrates with surface particle coverage: A mechanism for systematic surface laser damage , 2000 .

[10]  M. Feit,et al.  Rear-Surface Laser Damage on 355-nm Silica Optics Owing to Fresnel Diffraction on Front-Surface Contamination Particles. , 2000, Applied optics.

[11]  Albert F. Slomba,et al.  Combined advanced finishing and UV-laser conditioning for producing UV-damage-resistant fused-silica optics , 2002, SPIE Laser Damage.

[12]  Michel A. Josse,et al.  Laser damage to optical components induced by surface chromium particles , 2005, SPIE Laser Damage.

[13]  Francois Y. Genin,et al.  Laser-induced damage of fused silica at 355 and 1064 nm initiated at aluminum contamination particles on the surface , 1997, Laser Damage.

[14]  P. Combis,et al.  Numerical simulations for description of UV laser interaction with gold nanoparticles embedded in silica , 2004 .

[15]  J. Honig.  Cleanliness improvements of National Ignition Facility amplifiers as compared to previous large-scale lasers , 2004 .

[16]  Francois Jequier,et al.  LMJ superlaser for inertial confinement fusion , 2003 .

[17]  Laurent Lamaignère,et al.  Study of laser interaction with aluminum contaminant on fused silica , 2005, SPIE Laser Damage.

[18]  Roger Courchinoux,et al.  LMJ target area design and engineering physics inside the LMJ target chamber , 1999, Other Conferences.

[19]  T. Donval,et al.  Surface particulate contamination of the LIL optical components and their evolution under laser irradiation , 2007, SPIE Laser Damage.

[20]  John Honig,et al.  Experimental study of 351-nm and 527-nm laser-initiated surface damage on fused silica surfaces due to typical contaminants , 2005, SPIE Laser Damage.