Application of adaptive optics for controlling the NIF laser performance and spot211 size

摘要

The National Ignition Facility (NIF) laser will use a 192-beam multi-pass211u001earchitecture capable of delivering several MJ of UV energy in temporal pulse 211u001eformats varying from sub-ns square to 20 ns precisely-defined high-contrast 211u001eshapes. Each beam wavefront will be subjected to effects of optics 211u001einhomogeneities, figuring errors, mounting distortions, prompt and slow thermal 211u001eeffects from flashlamps, driven and passive air-path turbulence, and gravity-211u001edriven deformations. A 39-actuator intra-cavity deformable mirror, controlled by 211u001edata from a 77-lenslet Hartman sensor will be used to correct these wavefront 211u001eaberrations and thus to assure that stringent farfield spot requirements are met. 211u001eWe have developed numerical models for the expected distortions, the operation of 211u001ethe adaptive optic system, and the anticipated effects on beam propagation, 211u001ecomponent damage, frequency conversion, and target-plane energy distribution. 211u001eThese models have been extensively validated against data from LLNL's Beamlet, 211u001eand Amplab lasers. We review the expected beam wavefront aberrations and their 211u001epotential for adverse effects on the laser performance, describe our model of the 211u001ecorrective system operation, and display our predictions for corrected-beam 211u001eoperation of the NI