| 摘要 |
An external electronically illumination module, e.g. a liquid crystal cell 25, 26, 40, utilizing polirizing beam splitters 24 to split the light beam I from a projection lamp into two polarization states, selectively altering the state of each polarized light beam to reject a controlled portion of the light where the selectively altered beams are recombined and passed to the projection system optics. An intermediate layer 28 of LC polymer with a particular director profile is interposed between the LC material 32 and the glass substrate 30 on the light incident side. Thus, when the cell is biased, the intermediate layer 28 is between the glass substrate 30 and the LC boundary layer 34. A hydrid aligned LC layer 42 is provided between the glass substrate layers on the top light incident side and bottom 44, 46. This LC layer 42 is provided with a high pretilt, e.g., between about 45° and 90°, on the side adjoining the bottom substrate 44, and a low prtilt, e.e., less than 10°, on the side adjoining the bottom substrate 46. In either case, polarization of the reflections at the light incident side of the cell 26, 40 is not affected in such a way that contrast is reduced.
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