Patent ID: 8393777

Claim:
A luminance-preserving non-imaging backlight composed of a transparent dielectric, comprising a luminous source emitting light out of a bounded aperture that defines a y-z coordinate plane and has a surface normal that defines an x-axis; an input port receiving said light; an injector with said input port defining a first y-z boundary and a larger output port defining a second y-z boundary, said injector having an x-y profile that expands away from said input port to said output port, said x-y profile acting via total internal reflection to keep the x-y angular width of the source image inversely proportional to its luminance; said injector being a surface of revolution with axis on said source and a swept profile that is a first portion of an upper half of a compound parabolic concentrator (CPC) tilted in a negative z direction by its acceptance angle, said sweep profile acting to collimate light in a plane of said swept profile while azimuthally distributing said light along said output port; and a beam-expanding ejector comprising a planar waveguide in an x-y plane with its y-z boundary optically coupled to said output port of said injector so as to receive light therefrom, said ejector having a smooth upper surface of revolution with a profile that is a remaining portion of said CPC profile of said injector, said ejector having a reflective lower surface comprising microstructured facets of revolution coaxial with said surface of revolution of said upper surface, said facets comprising a face parallel to the flow-lines of said CPC profile and a connecting diagonal face with a tilt that reflects in a upwards z-direction said received light, said tilt of said diagonal face adjusted so that said upwardly reflected light is refracted into a collimated direction common to said facets.