Patent ID: 6654072
Filing Date: 2003-11-25
Classification: G02F

Abstract:
A polymer dispersed liquid crystal (PDLC) transmission phase grating capable of operating in the Bragg regime, the grating comprising:a cell having a pair of oppositely disposed substrates; a PDLC grating film contained within said cell, said PDLC film having a spatially periodic distribution of grating planes comprising polymer-rich regions and liquid crystal-rich regions, wherein the major constituent of said polymer-rich regions is a polymer, and wherein the liquid crystal constituent concentration within said liquid crystal-rich regions is greater than the liquid crystal constituent concentration within said polymer-rich regions; said polymer-rich regions characterized by a scalar optical dielectric constant with a value that remains substantially unperturbed by an electric field being applied in a direction perpendicular to said PDLC grating film; said liquid crystal-rich regions comprising a polymer matrix containing a liquid crystal-rich material, and said liquid crystal-rich material being characterized by optical dielectric tensor components; said optical dielectric tensor components comprising an ordinary component measured within said grating planes and an extraordinary component measured perpendicular to said grating planes, said components each having a value determined in the absence of said electric field; said liquid crystal-rich material having values of said optical dielectric tensor components capable of being altered by the application of said electric field; and said spatially periodic distribution having a spatial period of preselected value, and said electric field strength having a strength of preselected value, each said preselected value of said spatial period and said electric field strength being based upon the relationship between said scalar optical dielectric constant and said optical dielectric tensor components; wherein the PDLC transmission phase grating is rendered substantially transparent when subjected to said electric field during the application of light that is p-polarized and incident on the grating at Bragg angle.