Other

Thomas G Baur

Joel R Blum

Paul A Searcy

Roger H Badertscher

A birefringent optical filter and associated method are described which demonstrate improved performance for both fixed and tunable filter configurations. One exemplary embodiment involves an initial filter configuration, having an output polarizer, that exhibits an initial spectral filter response having an undesired transmission feature and a desired transmission feature. An additional polarizer follows the output polarizer and an adjustable retarder is disposed directly between the output polarizer and the additional polarizer to produce an overall spectral filter response that eliminates the undesired transmission feature, while passing the desired transmission feature. Another exemplary embodiment uses at least one reflective polarizer for passing light along the filter optical path, which light is characterized by a selected polarization, and for reflecting a rejected light that is characterized by a different polarization such that the rejected light is directed out of the optical path.

Advanced liquid crystal tunable filters and method

An improved polarized color video projector incorporates a light source to provide three collimated beams of linearly polarized light of blue, green, and red colors. A light modulator capable of imparting a video image in a light beam is positioned in each of the three colored beams to modulate the individual colored image components in each of the beams. A dischroic beam recombiner receives the modulated blue and green beams, and recombines them into a combined blue and green color image carrying beam. A polarization-selective/beam analyzer/recombiner receives the recombined blue and green beam and recombines it with the red beam. A retarder placed between the light modulator for the red beam and the polarization-selective/beam analyzer/recombiner, in the path of the modulated red beam, rotates the plane of polarization of the red beam to allow it to be recombined with the recombined blue and green beam in the polarization-selective/beam analyzer/recombiner. Projection apparatus receives the recombined blue, green, and red beams and projects them onto a display screen.

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Longmont, CO, United States of America

Thomas G Baur