US Patent 7312924 Polarizing multiplexer and methods for intra-oral scanning

A polarizing multiplexer includes a first arm with a first beam splitter to receive a first unpolarized light from an object and a first retarder coupled to the first beam splitter to generate a first right-hand circularly polarized (RHCP) beam. A normal incident beam splitter is used to receive the first RHCP beam. The multiplexer also includes a second arm with a second beam splitter to receive a second unpolarized light from an object; and a second retarder coupled to the second beam splitter to generate a left-hand circularly polarized (LHCP) beam, wherein the LHCP beam is reflected off the normal incident beam splitter and converted to a second RHCP beam. Light from both arms pass through the second retarder and are converted to p-polarized light before transmitting through the second beam splitter to an image sensor.