WIDE-ANGLE RUGATE POLARIZING BEAMSPLITTER

摘要

A polarizing beamsplitter includes an optical medium and a rugate filter embedded therein. The rugate filter has an average refractive index which varies with position on the rugate plane in the non-thickness direction, where the averaging is across the rugate film in the thickness direction. The variation in the rugate's average index compensates for variations in incident angle across a cone of a divergent light beam. In one embodiment, the period of the rugate is substantially constant across its surface. Most preferably, the amplitude of the rugate index variation has an apodizing amplitude envelope superimposed thereom to aid in coupling the rugate to a surrounding optical medium.