Ultra Compact Polarization Recycling System for White Light LED based Pico-Projection System

摘要

An ultra compact polarization recycling system, for white light LED based projectors, is proposed. White light LED is applied as the light source, which is composed of blue LED die and yellow phosphor. By optimizing the illumination optics and properly placing a reflective type polarization film, the light with non-useable polarization state will be reflected back and concentrated right on to the phosphor surface. The yellow phosphor will be re-excited by the blue spectrum component of the reflected light. More light energy will be recycled by attaching a piece of quarter wave plate before the reflective type polarization film. Experimental results show more than 30% light efficiency improvement.