Patent ID: 7845841

Claim:
An apparatus comprising: a light guide having first and second planar opposing surfaces with at least a portion of the first surface tilted with respect to the second surface to define a taper angle, the light guide further including sides disposed about the first and second surfaces; and a hologram disposed in the light guide, the hologram configured to eject injected light out of the light guide, the tilted first surface altering the distribution of angles that light is incident on the hologram as the light propagates through the light guide, wherein the hologram ejects light rays that are incident on the hologram within a range of acceptance angles, the taper angle is less than about one-half of the range of acceptance angles and is less than about 2 degrees, and the light guide is configured to allow some of the light rays to reflect more than once off of one of the first and second opposing surfaces so that the light rays are incident on the hologram within the range of acceptance angles.