Abstract

The University of Rochester’s OMEGA laser system requires each of its 300-mm-diam beams to have a high degree of intensity uniformity when focused on a target sphere. This task is largely accomplished through the use of the distributive phase plate (DPP). The DPP subdivides each laser beam into a multitude of small beamlets and introduces a randomized phase variation (of 0 or π radians) to each beamlet. The beamlets are then recombined by a focusing lens and directed on the deuterium/tritium target.^1,2 DPP fabrication can be accomplished two ways: by additive methods, such as coating with a thin film, or by subtractive methods, such as an ion milling process. The former process has the advantage of being the simpler of the two, but the latter yields the higher laser-damage threshold, and was recently determined to be the only acceptable method of DPP fabrication for the OMEGA Upgrade.

© 1992 Optical Society of America