The present invention provides a light emitting/receiving composite unit (1) for emitting and receiving lights, which includes a light source (3), an optical splitting unit (4) for splitting returning lights to the composite unit (1) into a plurality of lights, a polarizing unit (5) for increasing and...http://www.google.com/patents/US6980303?utm_source=gb-gplus-sharePatent US6980303 - Light-emitting/receiving combined unit and displacement sensors using the same
