Optical: systems and elements – Holographic system or element – Using a hologram as an optical element
Patent
1992-12-31
1994-06-28
Gross, Anita P.
Optical: systems and elements
Holographic system or element
Using a hologram as an optical element
359 40, 359 64, 359 65, 353122, 353DIG3, 353DIG5, G02F 1133, G02F 11335, G03B 2100
Patent
active
053252187
ABSTRACT:
A liquid crystal display (LCD) panel employs a cholesteric polarizer which passes light of a first circular polarization, but reflects light of a second circular polarization. The LCD panel may be monochrome or color; in the color embodiments, several different color filters are used, each having one or more cholesteric polarizers tuned to a specific bandwidth in the visible spectrum. These polarizers replace dyed (neutral or dichroic) polarizers of prior art LCD panels, and provide improved color purity. The invention may be enhanced by providing a light recycling scheme whereby the handedness of the circularly polarized light reflected by the polarizers is changed and redirected back to the polarizers. This recycling scheme may also be adapted to provide an overhead projector having a high output polarized light source, particularly useful in conjunction with an LCD panel.
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Tritle Gary L.
Willett Stephen J.
Griswold Gary L.
Gross Anita P.
Kirn Walter N.
Minnesota Mining and Manufacturing Company
Musgrove Jack V.
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