Optical: systems and elements – Holographic system or element – Using a hologram as an optical element
Patent
1993-05-14
1995-05-23
Lerner, Martin
Optical: systems and elements
Holographic system or element
Using a hologram as an optical element
359 28, 359 34, 359 69, 359105, 359599, G02B 532, G02B 502, G02F 11335
Patent
active
054186315
ABSTRACT:
Methods of recording and using holographic diffusers are disclosed for use with edge-lit backlight assemblies for transmissive flat-panel displays such as LCDs. When the holographic diffuser is supported against a surface of a backlight-emitting substrate it is operative to scatter the light in the direction of the display panel largely independent of angle of incidence. The recording methods may be used to produce both transmissive- and reflective-type diffusers, which may be employed simultaneously. In one embodiment a transmissive diffuser is used with a reflector and a cholesteric liquid crystal (CLC) polarizer. In this configuration, scatter lobes exhibiting the correct circular polarization are passed by CLC polarizer, whereas radiation of the opposite handedness is redirected toward the reflector, which converts the handedness into the form passable by the CLC polarizer. A quarter-wave plate, added between the CLC polarizer and the display, is operative to transform the circularly polarized scattered radiation into linearly polarized light, obviating the requirement for an additional rear polarizer on the LCD display. An application incorporating a secondary information source, such as an intensified night-vision image, is also described.
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Pennington et al, "Fast Wave Optical Guide Couplers Using Holographic Elements," IBM Technical Disclosure Bulletin, vol. 13, No. 8, Jan. 1971, pp. 2280 to 2281.
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Kaiser Optical Systems, Inc.
Lerner Martin
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