Contrast enhancement and ghost elimination, for reflective light

Optical: systems and elements – Holographic system or element – Using a hologram as an optical element

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359 65, 359 73, 359495, 353122, G02F 1133, G03B 2100

Patent

active

052687759

ABSTRACT:
A reflective liquid crystal light valve projection system employs a polarizing beam splitter (16) to reflect light from a high intensity arc lamp (10) to a liquid crystal light valve (34) that is controlled by an image generator (36). Light reflected from the liquid crystal light valve is transmitted through the polarizing beam splitter (16) to a projection lens (38) and projected on a screen. Ghost images of the arc lamp source and diminished contrast are caused by light reflected from surfaces of the lens elements back to the liquid crystal light valve and then retroreflected back through the lens. The ghost images and diminished contrast are eliminated by interposing a broad band quarter wave plate between the lens and the polarizing beam splitter.

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