Patent ID: 6072631
Filing Date: 2000-06-06
Classification: G02B,G03H

Abstract:
A diffractive homogenizer for producing more than one preselected illumination patterns having a preselected intensity profile within each of the preselected patterns which responds to a beam of substantially monochromatic radiation directed thereon, the diffractive homogenizer comprising:a plurality of sub-elements, each sub-element contributing a portion of the preselected intensity profile of at least one of the preselected illumination patterns;wherein each sub-element is comprised of a plurality of pixels, each of said pixels producing a selected phase shift in the radiation;wherein each sub-element forms a selected contribution, said contribution combining additively to form said preselected illumination pattern;and wherein said diffractive homogenizer includes at least one of the following compensations;pixel phase shifts are selected to compensate for the finite spatial coherence of the radiation, said compensation is performed by determining a convolution function that accounts for a difference between an image using coherent light and an image formed using real light having limited spatial coherence,a more uniform distribution of radiation is created within a numerical aperture of illumination by adjusting the selected contribution from each sub-element, orthe preselected intensity profile is selected to be non-uniform in order to compensate for one or more repeatable manufacturing process variation.