Optical: systems and elements – Holographic system or element – Using a hologram as an optical element
Patent
1991-11-08
1992-12-15
Sikes, William L.
Optical: systems and elements
Holographic system or element
Using a hologram as an optical element
359 63, 359 70, 359 77, 359100, G02F 113
Patent
active
051722577
ABSTRACT:
A twisted ferroelectric liquid-crystal optical modulator in which a ferroelectric smectic C* liquid crystal (26) is filled into the gap between two alignment layers (18, 20) aligning the adjacent liquid crystal in two perpendicular directions parallel to the alignment layers. The ferroelectric liquid crystal has a tilt angle of 45.degree. and is aligned with the tilt angle parallel to the buffing direction of the alignment layer. Thereby, the liquid-crystal molecules (32), absent any applied field from electrodes (14, 18), slowly twists through 90.degree. across the gap, and the liquid crystal waveguides light linearly polarized by an input polarizer (22) so that it passes a perpendicularly arranged output polarizer (24). However, a strong electric field causes the ferroelectric molecules to untwist and line up in parallel. Waveguiding is destroyed, and the cell does not transmit. Intermediate voltages cause partial untwisting and partial waveguiding. Thus, variations in the applied voltages can modulate the light according to a gray scale.
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Bell Communications Research Inc.
Guenzer Charles S.
Mai Huy K.
Sikes William L.
Suchyta Leonard Charles
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