Abstract: A clean room ceiling light fixture formed as a sealed housing with a downwardly-directed light emitting aperture. A heat sink fixed within and spaced from the housing defines a cable raceway inside the housing. A plurality of LEDs are mounted on the heat sink. A high refractive index (polycarbonate) reflector coupled to each LED efficiently directs the LED's light through the aperture into the clean room. The LEDs and/or reflectors can be anti-reflectively coated to improve light transmission efficiency. A refractive index matching compound applied between each LED-reflector pair further improves light transmission efficiency. A spectrally selective filter material prevents ultraviolet illumination of clean rooms used for lithographic processes which are compromised by ultraviolet rays. A holographic diffusion lens and/or variable transmissivity filter can be provided to uniformly distribute the LEDs' light through the aperture.

Abstract: The color temperature of light emitted by a luminaire having a hollow prismatic light guide is varied to counteract aesthetically undesirable reddening gradient of the emitted light. Reddening is caused by the light guide's dielectric material, which absorbs blue light rays such that proportionately more red than blue rays are guided to the light guide's far end than to points near the guide's light input end. Flare light rays which escape through the light guide near its light input end are color filtered and reflected back into the light guide. The filter color lies within a CIE-1931 chromaticity diagram {4800° Kelvin; 570 nm; 600 nm} color gamut triangle. Color filtering absorbs blue flare rays as a function of distance along the guide, imparting a near-end reddening gradient to the emitted light in inverse proportion to the far-end reddening gradient, giving the emitted light a constant apparent color, independent of distance along the guide.

Abstract: The color temperature of light emitted by a luminaire having a hollow prismatic light guide is varied to counteract aesthetically undesirable reddening gradient of the emitted light. Reddening is caused by the light guide's dielectric material, which absorbs blue light rays such that proportionately more red than blue rays are guided to the light guide's far end than to points near the guide's light input end. Flare light rays which escape through the light guide near its light input end are color filtered and reflected back into the light guide. The filter color lies within a CIE-1931 chromaticity diagram {4800° Kelvin; 570 nm; 600 nm} color gamut triangle. Color filtering absorbs blue flare rays as a function of distance along the guide, imparting a near-end reddening gradient to the emitted light in inverse proportion to the far-end reddening gradient, giving the emitted light a constant apparent color, independent of distance along the guide.

Abstract: A clean room ceiling light fixture formed as a sealed housing with a downwardly-directed light emitting aperture. A heat sink fixed within and spaced from the housing defines a cable raceway inside the housing. A plurality of LEDs are mounted on the heat sink. A high refractive index (polycarbonate) reflector coupled to each LED efficiently directs the LED's light through the aperture into the clean room. The LEDs and/or reflectors can be anti-reflectively coated to improve light transmission efficiency. A refractive index matching compound applied between each LED-reflector pair further improves light transmission efficiency. A spectrally selective filter material prevents ultraviolet illumination of clean rooms used for lithographic processes which are compromised by ultraviolet rays. A holographic diffusion lens and/or variable transmissivity filter can be provided to uniformly distribute the LEDs' light through the aperture.

Abstract: Image display apparatus incorporating an enclosure having substantially opaque, substantially reflective interior surfaces. A light source emits light rays within the enclosure. An image-bearing surface is mounted in a front portion of the enclosure. The image-bearing surface bears a predefined image having transmissivity and reflectivity characteristics which vary as a function of position on the image-bearing surface, such that a substantial portion of the image is substantially non-transmissive and substantially reflective, and the remaining non-substantial portion of the image is substantially transmissive and substantially non-reflective.