Abstract: An illumination system that has an output luminance (brightness) LO that is greater than the intrinsic output luminance (brightness) LI of the light emitting diodes used within the system. The system utilizes one or more light emitting diodes having highly reflective surfaces and recycles a portion of the light generated by the light emitting diodes back to the light emitting diodes in order to enhance the effective luminance. The illumination system includes a light-reflecting cavity and one or more highly reflective light emitting diodes having total surface area AS mounted inside the cavity, either on the interior surfaces of the cavity or within the cavity volume. The cavity has a light output aperture of area AO. The light emitting diodes have reflectivity RS. The exposed inside surfaces of the light-reflecting cavity have reflectivity RC. In order to achieve enhanced brightness, it is required that the area of the light output aperture AO be less than the total area AS of the light emitting diodes.

Abstract: An illumination system that has an output luminance (brightness) LO that is greater than the intrinsic output luminance (brightness) LI of the light emitting diodes used within the system. The system utilizes one or more light emitting diodes having highly reflective surfaces and recycles a portion of the light generated by the light emitting diodes back to the light emitting diodes in order to enhance the effective luminance. The illumination system includes a light-reflecting cavity and one or more highly reflective light emitting diodes having total surface area AS mounted inside the cavity, either on the interior surfaces of the cavity or within the cavity volume. The cavity has a light output aperture of area AO. The light emitting diodes have reflectivity RS. The exposed inside surfaces of the light-reflecting cavity have reflectivity RC. In order to achieve enhanced brightness, it is required that the area of the light output aperture AO be less than the total area AS of the light emitting diodes.

Abstract: An optical illumination system comprising a waveguide that accepts light generated by a light source and transmits the light via total internal reflection. Attached on one face of the waveguide is an array of microprisms, with each microprism having an light input surface, a light output surface and at least one sidewall which is tilted at an angle from the direction normal to the surface of the waveguide and further comprising at least two planar faces such that light escapes from the waveguide, reflects off the tilted sidewalls and emerges from the microprism as a spatially directed light source. An array of microlenses may be positioned to accept the output of the microprisms so that the light exiting from the microlenses is a substantially collimated light source. The optical illumination system is advantageous for any application that requires a non diffuse or substantially collimated light source that is both energy efficient and contained in a low profile assembly.