Slim coherent backlight unit for holographic display using full color holographic optical elements

Abstract: The coherent backlight unit (BLU) using holographic optical element (HOE) for full-color flat-panel holographic display is proposed. The HOE BLU consists of two reflection type HOEs which change the optical beam path and shape by diffraction. The illumination area of backlight is 150 mm x 90 mm and the thickness is 10 mm, which is slim compared to other conventional coherent backlight units for holographic display system. This backlight unit exhibits a total efficiency of 8.0％ at Red (660 nm), 7.7％ at Green (532 nm), 3.2％ at Blue (460 nm) using optimized recording conditions for each wavelength. As a result, we could get a bright full color hologram image.