Polarization recycling method for light-pipe-based optical engine

In this paper, a polarization recycling method is proposed for a light-pipe-based liquid crystal on silicon (LCoS) pico-optical engine. The method is based on making use of the virtual light sources array forming at the light pipe's input surface. With traditional imaging optics, the virtual light sources array can be imaged to a plane after the light pipe, where the separated beams array can be obtained. By applying the polarization conversion system to the separated beams, the incoming unpolarized light can be converted to polarized light. The polarized light is then collected and transferred to the LCoS panel through the relay system. This new polarization recycling method can highly improve the light efficiency. A design example of a 0.29 in. (7.366 mm) color-filter LCoS pico-optical engine with 852 x 480 resolution is listed. High light efficiency of about 10.5 lm per LED Watt and high irradiance uniformity of about 95% has been achieved. The thickness of the optical engine is 8 mm. (C) 2013 Optical Society of America