Apodised aperture assembly for high power lasers

Claim 1

An apodised aperture assembly for minimizing deleterious diffraction effects in a laser beam comprising: a support assembly having an aperture extending therethrough, a pair of window means positioned in said support assembly and in alignment with said aperture, said support assembly comprising a central section and two outer sections secured to said central section on opposite sides thereof, each of said support assembly sections being provided with a centrally located aperture having portions thereof of a cross section less than the periphery of said pair of window means, said pair of window means being substantially optically neutral and configured to define within said aperture a chamber having a thickness near zero at the center thereof and increasing thickness with increasing radius from the center thereof, one of said pair of window means comprising a lens having a convex surface, the other of said pair of window means comprising an optical element having a flat surface in abutment with said central section of said support assembly, said flat surface of said optical element being positioned closely adjacent said convex surface of said lens so as to define in cooperation with said aperture of said central section of said support assembly said radially increasing thickness chamber containing an absorbing liquid, said lens being substantially positioned in said aperture of said central section of said support assembly and retained therein by one of said two outer sections of said support assembly, said optical element being retained in abutment with said central section by the other of said outer sections, said chamber being substantially defined within said aperture of said central section of said support assembly, sealing means positioned about said chamber intermediate said window means and said support assembly comprising a first seal located intermediate said lens and said central section of said support assembly and a second seal located intermediate said optical element and said central section of said support assembly, and absorber material positioned in said chamber, said absorber material having a thickness near zero in the center and increasing in thickness with increasing radius, whereby a smoothly varying transmission profile is provided as a laser light beam passes through said aperture assembly minimizing diffraction effects.