ILLUMINATION DEVICE WITH HOLOGRAPHIC LIGHT GUIDE

摘要

An illumination device includes a holographic film 89 and a light source 93, such as a point light source. The point light source 93 is positioned at an edge of the holographic film and has a light emitting face that faces the edge of the holographic film 89. The holographic film 89 includes a hologram formed of diffractive refractive index structures. The density of the diffractive refractive index structur-es increases with increasing distance from the light source 93. Light is propagated from the light source 93 through the holographic film 89, such as by total internal reflection. The diffractive refractive index structures turn the light, thereby causing the light to propagate out of the holographic film 89 in a desired direction. In some embodiments, the light propagating out of the holographic film 89 has a high uniformity across the surface of the holographic film 89.