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Title: Improved Spatial Filter for high power Lasers

A new pinhole architecture incorporates features intended to reduce the rate of plasma generation in a spatial filter for high-energy laser pulse beams. An elongated pinhole aperture is provided in an apertured body for rejecting off-axis rays of the laser pulse beam. The internal surface of the elongated aperture has a diameter which progressively tapers from a larger entrance cross-sectional area at an inlet to a smaller output cross-sectional area at an outlet. The tapered internal surface causes off-axis rays to be refracted in a low density plasma layer that forms on the internal surface or specularly reflected at grazing incidence from the internal surface. Off-axis rays of the high-energy pulse beam are rejected by this design. The external surface of the apertured body adjacent to the larger entrance cross-sectional area at the inlet to the elongated aperture is angled obliquely with respect to the to direction of the path of the high-energy laser pulse beam to backscatter off-axis rays away from the high-energy pulse beam. The aperture is formed as a truncated cone or alternatively with a tapered square cross-section. The internal surface of the aperture is coated with an ablative material, preferably high-density material which can be depositedmore » with an exploding wire.« less
Authors:
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Publication Date:
OSTI Identifier:
782763
Report Number(s):
PATENTS-US--A9089126
US patent application 9-089,126; TRN: AH200127%%59
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Patent Application
Resource Relation:
Patent File Date: 1998 Jun 01; Other Information: PBD: 1 Jun 1998
Research Org:
Lawrence Livermore National Lab., CA (US)
Sponsoring Org:
US Department of Energy (US)
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; APERTURES; DESIGN; LASERS; FILTERS; BEAM SEPARATORS; LASER RADIATION