Spatial filter lens design for the main laser of the National Ignition Facility

摘要

Abstract: The National Ignition Facility (NIF), being designed and constructed at Lawrence Livermore National Laboratory, comprises 192 laser beams. The lasing medium is neodymium in phosphate glass with a fundamental frequency (1 approximately ega@) of 1.053 $mu@m. Sum frequency generation in a pair of conversion crystals (KDP/KD*P) will produce 1.8 megajoules of the third harmonic light (3 approximately ega or $lambda $EQ 0.351 $mu@m) at the target. The purpose of this paper is to provide the lens design community with the current lens design details of the large powered optics in the Main Laser. This paper describes the lens design configuration and design consideration of the Main Laser. The Main Laser is 123 meters long and includes two spatial filters: one 23.5 meters and one 60 meters. These spatial filters perform crucial beam filtering and relaying functions. We shall describe the significant lens design aspects of these spatial filter lenses which allow them to successfully deliver the appropriate beam characteristic onto the target.!0