Optical: systems and elements – Holographic system or element – Using a hologram as an optical element
Patent
1992-06-26
1995-05-30
Sikes, William L.
Optical: systems and elements
Holographic system or element
Using a hologram as an optical element
430 20, 430 54, 359 55, 382199, G02F 113
Patent
active
054207096
ABSTRACT:
An edge image extraction light modulator forms an edge portion image corresponding to a boundary between two optically equalized portions of a liquid crystal layer. Each portion has a different bistable state and an edge portion optically distinct from the two optically equalized portions. An optical image is written onto the light valve while applying a voltage between two transparent electrode layers of the light valve to effect switching between a first stable optical axis and a second stable optical axis. The light valve is illuminated and the edge portion of the written image is read. A first and a second polarizer are in crossed-Nicols position so that the two optically equalized portions comprise a portion having the written image except for the edge portion thereof and a non-written portion. The edge portion is not optically equal to the two optically equal portions and can thus be detected. A method of driving the edge image extraction light modulator includes writing an optical image onto the light valve by irradiating a photoconductive layer with light. A first pulse voltage is applied to erase and reset the light valve, and a second pulse voltage is applied, having a polarity opposite that of the first pulse voltage, to generate carriers diffusing in the photoconductive film to impart an electric field to the liquid crystal layer and form an enlarged image of the optical image in the light valve. A third pulse voltage, having the same polarity as that of the first pulse voltage, erases a part of the enlarged image except for an edge portion thereof to form an edge enhanced image in the light valve.
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Ebihara Teruo
Kato Naoki
Sekura Rieko
Yamamoto Shuhei
Yamanaka Junko
Parker Kenneth
Seiko Instruments Inc.
Sikes William L.
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