Patent ID: 7990600
Filing Date: 2011-08-02
Classification: G02B,G02F,H04N

Abstract:
1. A transmissive, photoconductive optically addressed spatial light modulator comprising: first and second optically transparent electrode structures; a photoconductive material structure and an electro-optic light modulating structure included between the first and second electrode structures, the photoconductive material structure at its operating temperature being responsive to a first wavelength and flux range of light and substantially nonresponsive to a second wavelength and flux range of light, the first and second wavelength ranges being different from each other and the flux of the second flux range of light being substantially larger than the first flux range of light; the photoconductive material structure has a variation of composition such that photoexcited election- and hole-charge carriers generated by light within the first wavelength and flux range of light do not exit from the light modulator to any substantial extent; and local variations of polarization of the photoconductive material structure resulting from local variations in the quantity of light within the first wavelength and flux range of light subject to an electric field produced by an externally applied AC bias potential across the two electrode structures cause local variations of a voltage developing across the electro-optic light modulating structure sufficient to produce local variation of an optical property of at least some electro-optic material within the electro-optic light modulating structure to the extent an optical property of light within the second wavelength and flux range of light is modulated locally as it passes through the entire structure of the two electrode structures, the photoconductive material structure, and the electro-optic light modulating structure; in which the electro-optic light modulating structure contains a layer of liquid crystal type material; in which the electro-optic light modulating structure further comprises opposed surface alignment layers between which the liquid crystal material layer is contained, the surface alignment layers conditioned to produce substantially homeotropically aligned directors within the liquid crystal material in the absence of an electric field.