Light valve projection system with improved writing control and reduced fluid degradation

Claim 1

An improved light valve comprising: a light modulating fluid; a light source positioned to project light through said light modulating fluid; electron beam means for scanning an electron beam to form a raster, wherein there is formed within said raster at least one diffraction grating in said light modulating fluid to diffract incident light from said light source for projection onto a viewing surface, said electron beam means including vertical and horizontal deflection means for controlling the position of said electron beam and means for depositing charge to control depth and spacing of grooves in said diffraction grating thereby controlling the diffraction of said incident light, and a sharp-cutoff filter positioned between said light source and said light modulating fluid, said sharp-cutoff filter being an optical filer having characteristics where below a specified wavelength the transmissivity is near zero percent over a desirable range of the electromagnetic spectrum, including at least that part of the ultraviolet spectrum responsible for deleterious effects on the light modulating fluid, and near 100% over a range of the electromagnetic spectrum which is used for information imaging with the transition from near zero percent to near 100% transmission being defined by a steep positive going slope, said sharp-cutoff filter allowing the operation of the light valve at high brightness levels while reducing attendant degradation effects of said light modulating fluid and maintaining desired writing parameters of the light valve by decreasing the temperature of said light modulating fluid for said high brightness levels.