Compact, high-brightness LED illumination for projection systems

— An arrangement consisting of a polarizing beam splitter, retarders, and dichroic mirrors provides a compact and efficient combiner for red, green, and blue light from separate LED packages. The resulting illuminating beam is unpolarized. In initial tests, a 0.55-in. DMD engine based on this illuminator produced an on-screen flux of 188 lm from 58 W of LED input power, using an f/2.4 pupil. Subsequent work with the same imager and LED set has resulted in a compact and efficient 300-lm projector.