Importance

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Abstract

The present invention provides a high brightness subtractive color filter formed by an electro-optic modulator positioned between two retarder stacks. The second retarder stack echoes the first retarder stack, having the same sequence of retardances but in reverse order and having an orientation rotated with respect to the first stack. The modulator changes the apparent orientation of the second stack so that, in a first switching state of the modulator the two stacks cooperate in filtering the spectrum of input light, and in a second switching state they vanish, leaving white light. Two or more stages can be used in series, each stage providing independent analog control of a primary color. One preferred embodiment eliminates internal polarizers between stages, thereby providing a full-color display with only two neutral polarizers. Hybrid filters can be made using the filter of this invention in combination with other active or passive filters. The color filters of this invention can be used in many applications, particularly in the areas of recording and displaying color images. They can be arranged in a multi pixel array and can be optically addressed.

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First Claim