Patent ID: 6490087
Filing Date: 2002-12-03
Classification: G02B,H04N,Y10S

Abstract:
A method for improving the contrast of a projection system employing at least two reflective, polarization converting, pixelized panels comprising passing light from a light source to the two pixelized panels, modulating the light at the two pixelized panels, and passing the modulated light to a projection lens, wherein:(a) between the light source and the projection lens, a first portion of the light passes through first and second half wave plates and a second portion of the light passes through third and fourth half wave plates, each half wave plate being oriented so as to transform S polarized light to P polarized light and P polarized light to S polarized light; (b) between the light source and each of the two pixelized panels, the light interacts with two polarization diagonals, the light having S polarization for one of said interactions and having P polarization for the other of said interactions; (c) between each of the two pixelized panels and the projection lens, the light interacts with two polarization diagonals, the light having S polarization for one of said interactions and having P polarization for the other of said interactions; and (d) all image-forming light that reaches the projection lens from the light source has: (i) interacted with a polarization diagonal between the light source and a pixelized panel and, after said interaction, has had primarily P polarization; and (ii) interacted with a polarization diagonal between said pixelized panel and the projection lens and, after said interaction, has had primarily P polarization; where for light having P polarization, an interaction with a polarization diagonal involves primarily transmission through the diagonal, and where for light having S polarization, an interaction with a polarization diagonal involves primarily reflection from the diagonal.