Holographic diffraction grating for side lighting of liquid-crystal displays

Abstract

This paper discusses the properties of a reflective-type holographic diffraction grating intended for the output of radiation from a lightguide wedge to the screen of a liquid-crystal display. The main parameters of the grating (the spatial frequencies of the lines and the distribution of the reflectances of light over its surface) that provide uniform illumination of the display screen in the green part of the spectrum are determined. The nonuniformity of the illumination of the screen in the blue and red parts of the spectrum is estimated. Experimental samples of a holographic diffraction grating and of a replica of it have been fabricated, and a comparison has been made of the light flux directed into the side of a display screen in a classical version of a lighting device and in a version based on a holographic grating.