Patent ID: 6262845
Filing Date: 2001-07-17
Classification: G03F

Abstract:
A scatter plate for providing a source of partially coherent illumination, comprising:a thin plate having first and second axes defining a surface, said surface having a length and a width,said surface comprising at least eight zones of about coequal area, wherein each of said zones comprises a long narrow rectangular or arcuate region bounded by substantially parallel first and second edges,said zones arranged as a stacked array such that each of said zones lies adjacent to at least one other zone along about all of the length of either or both of said first and second parallel edges, each of said zones further comprising:a blazed diffraction grating filling substantially all of said region, said diffraction grating comprising a plurality of substantially parallel fringes, wherein each of said fringes comprises a staircase wedge having a landing and at least three steps above said landing,each said diffraction grating having an orientation unique from every other grating on said scatter plate and a spatial frequency, wherein said orientation and said spatial frequency are chosen to diffract light into a predetermined, non-repeating location within a condenser means entrance pupil.