Abstract: An illumination light source includes an incoherent solid state light source adapted to emit light over at least one light emission surface and having a total light emission surface area S0; a light circulation device including at least one light receiving surface adapted to receive the light from the incoherent solid state light source, and a light extraction area having a first surface area S1; and a light extraction device for extracting the light from the light circulation device at the light extraction area, wherein S1<S0. Accordingly, the apparent brightness of the light is increased by distributing it over a smaller area.

Abstract: Light that is emitted from an LED chip at a first angle of incidence or less relative to the LED chip is permitted to leave the LED package. Light emitted from the LED chip at an angle of incidence greater than that is kept from leaving the LED package and is recycled back within the LED package. The recycled light is reemitted from the LED package after its angle of incidence relative to the LED chip has been changed, for example by passing it through a diffuser.

Abstract: Light that is emitted from an LED chip at a first angle of incidence or less relative to the LED chip is permitted to leave the LED package. Light emitted from the LED chip at an angle of incidence greater than that is kept from leaving the LED package and is recycled back within the LED package. The recycled light is reemitted from the LED package after its angle of incidence relative to the LED chip has been changed, for example by passing it through a diffuser.

Abstract: An illumination light source includes an incoherent solid state light source adapted to emit light over at least one light emission surface and having a total light emission surface area S0; a light circulation device including at least one light receiving surface adapted to receive the light from the incoherent solid state light source, and a light extraction area having a first surface area S1; and a light extraction device for extracting the light from the light circulation device at the light extraction area, wherein S1<S0. Accordingly, the apparent brightness of the light is increased by distributing it over a smaller area.

Abstract: Method and apparatus of coupling light into a light guide using error detecting and correcting systems. A rectangular light guide is mated with an X-axis optical fiber and with a Y-axis optical fiber. An X-axis photodetector senses light that couples from the light guide into the X-axis optical fiber, while a Y-axis photodetector senses light that couples from the light guide into the Y-axis optical fiber. An error detector compares the outputs of the X-axis and the Y-axis photodetectors to produces error signals that depend on the X-axis, the Y-axis, and the Z-axis positional errors. The errors signals are applied to an error correcting system that adjusts the relative position of the light guide and the light directed onto the light guide.

Abstract: A light engine for a single-panel scrolling-color projection system includes a source filter for filtering out unwanted components from the output spectrum of the source lamp prior to scrolling, and beam splitting filters having filtering characteristics chosen to mask the beamsteering effects caused by the angle sensitivity of the recombination filters. Such a light engine produces color stripes which maintain stable colors during scrolling, without the use of splitting and recombining filters with low angle sensitivities.

Abstract: An apparatus for improved contrast in projection optical systems consists of a polarizing beam splitter (PBS) in combination with two or more waveplates whose fast exes are aligned perpendicular to each other. The apparatus has an effective broadband frequency response that is better than that of the individual retarders acting alone, and through the selection of a birefringence factor and thickness of the individual retarders, wavelength dependencies are minimized.

Abstract: A light engine for a single-panel scrolling-color projection system includes a source filter for filtering out unwanted components from the output spectrum of the source lamp prior to scrolling, and beam splitting filters having filtering characteristics chosen to mask the beamsteering effects caused by the angle sensitivity of the recombination filters. Such a light engine produces color stripes which maintain stable colors during scrolling, without the use of splitting and recombining filters with low angle sensitivities.

Abstract: An apparatus for improved contrast in projection optical systems consists of a polarizing beam splitter (PBS) in combination with two or more waveplates whose fast exes are aligned perpendicular to each other. The apparatus has an effective broadband frequency response that is better than that of the individual retarders acting alone, and through the selection of a birefringence factor and thickness of the individual retarders, wavelength dependencies are minimized.

Abstract: Apparatus is disclosed for directing flashes of light into the eyes of a user. LED's 17 are mounted in the eyepieces of goggles 3 or spectacles 43 to face the eyes of a wearer. The goggles 3 or spectacles 43 are opaque and are provided with opaque flanges 9 to avoid ambient light reaching the eyes of a wearer. The frequency and brightness of the flashes is variable. The device is useful in the treatment of migraine, pre-menstrual syndrome, insomnia and nervous tension. Alternatives are disclosed using remote light sources 51 and optic fibres 53 or mirrors 57, mechanical or electro-optic shutters 59, 61, and arrangements using a common light source 51 for both eyes.