SPATIAL FILTER PINHOLE FOR HIGH-ENERGY PULSED LASERS

Spatial filters are essential components for maintaining high beam qua lity in high-energy pulsed laser systems. The long-duration (21 ns) hi gh-energy pulses envisioned for future inertial-confinement fusion dri ve systems, such as the U.S. National Ignition Facility (NIF), are lik ely to lead to increased plasma generation and closure effects within the pinholes in the spatial filters. The design goal for the pinhole s patial filter for the NIF design is to remove small-angle scatter in t he beam to as little as a +/- 100-mu rad divergence. It is uncertain w hether this design requirement can be met with a conventional pinhole design. We propose a new pinhole architecture that addresses these iss ues by incorporating features intended to reduce the rate of plasma ge neration. Initial experiments with this design have verified its perfo rmance improvement relative to a conventional pinhole design. (C) 1998 Optical Society of America.