Importance

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Abstract

A light collection system for projectors, such as light valve projectors, has a compound reflector associated with an arc lamp. The compound reflector includes an ellipsoidal reflector positioned to collect a portion of the light from the arc lamp and reflect a direct image of the light in a beam to an image forming plane of the projector and a spherical reflector positioned to collect another portion of the light from the arc lamp and reflect it back through the gap of the arc lamp to the ellipsoidal reflector to be reflected as a secondary image of the light from the lamp in the beam. The ellipsoidal and spherical reflectors are formed as full, uninterrupted surfaces of revolution. To provide uniform light distribution, the beam is directed through a pair of spaced lens plates, each having corresponding arrays, in rows and columns, of rectangular lenticules. The adjacent focus of the ellipsoidal reflector is centered in the arc, while the center of curvature of the spherical reflector, in order to avoid transmission loss through the arc, is displaced to a portion of the gap of the lamp which is relatively free of the arc. For maximum light efficiency, the direct image is focused just to one side, and the secondary image is focused just to the other side of the image forming plane.

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First Claim