Large screen video display systems and methods therefor

Abstract

A large screen display system for video modulated collimated light provides superior contrast and brightness, in a shallow depth configuration if desired. A single modulated laser beam which may have different color components is raster scanned, defining a beam envelope which is then expanded along an adequately long optical path length within a confined volume and directed toward a display screen on which the beam impinges. The optical system may selectively redirect the available light energy into a viewing volume with optical gain and with high contrast. In a particularly compact example of a rear projection system, the optical path is defined by successive reflecting elements adjacent and substantially coextensive with the screen, which cause the beam path to traverse behind the screen in successive path segments. The beam envelope is then directed obliquely against the display plane, but differentially redirected so as to be transmitted orthogonally outwardly. Optical gain may be further improved by an array of lens elements at the display plane defining diffuse point light sources to an observer, and the lens elements further may anistropically shape the far field distribution of the light. Light absorbing means disposed at the display plane can be used to enhance color contrast substantially.