Patent ID: 6650450
Filing Date: 2003-11-18
Classification: G02B,H04B

Abstract:
A light transmitting and receiving device comprising:a light projecting unit having an optical axis of projection; a light receiving unit having an optical axis of reception; and an optical member, disposed where the optical axis of projection intersects the optical axis of reception, said optical member including therewithin a light beam splitter which reflects one of a light beam from said light projecting unit and a light beam travelling to said light receiving unit while transmitting therethrough the other of the light beam from said light projecting unit and the light beam travelling to said light receiving unit, wherein said optical member has (a) a transmission and reception surface, spaced from said light beam splitter and being an exterior surface of said optical member so that said transmission and reception surface is the last surface of said optical member through which the light beam from said light projecting unit is transmitted and (b) a surface opposing the transmission and reception surface, wherein the transmission and reception surface and the opposing surface are mutually parallel and are inclined with respect to the optical axis of transmission and reception along which the transmitted light beam exits from the transmission and reception surface so that the optical axis of transmission and reception is not perpendicular to the transmission and reception surface, wherein the optical axis of projection and the optical axis of reception are perpendicular to each other, and wherein the inclination angle is such that the principal ray of the light beam reflected from the transmission surface is not received by said light receiving unit.