Light transmitting and receiving device having optical member with beam splitter

An optical member for use with a light transmitting and receiving apparatus, the apparatus having (a) light projection means for projecting light, the light projection means having an optical axis of projection, and (b) light receiving means for receiving light, the light receiving means having an optical axis of reception, wherein said optical member is disposed where the optical axis of projection and the optical axis of reception intersect, said optical member comprising:

• a top surface;
• a bottom surface opposing and parallel to the top surface;
• a light entrance surface for receiving light from the light projection means;
• a side surface opposing and parallel to the light entrance surface;
• a light transmission and reception surface extending between the light entrance surface and the side surface;
• a light exit surface opposing and parallel to the light transmission and reception surface;
• and
• a polarizing light beam splitting surface inside said optical member,
• wherein each of the top surface, the bottom surface, the light entrance surface, the side surface, the light transmission and reception surface, and the light exit surface is an exterior surface of said optical member,
• wherein light from the light projecting means enters the light entrance surface, is reflected by the polarizing light beam splitting surface, and exits from said optical member through the light transmission and reception surface, while incoming light passes through the light transmission and reception surface, is transmitted through the polarizing light beam splitting surface, and exits through the light exit surface to the light receiving means, and
• wherein the central beam of the light exiting through the light transmission and reception surface is inclined with respect to a line normal to the light transmission and reception surface,
• wherein said light transmission and reception surface is spaced from said polarizing light beam splitting surface and since said light transmission and reception surface is an exterior surface of said optical member, said light transmission and reception surface is the last surface of said optical member through which the light beam from said light projecting means is transmitted,
• wherein the optical axis of projection and the optical axis of reception are perpendicular to each other.

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 transmission surface, spaced from said light beam splitter and being an exterior surface of said optical member so that said transmission surface is the last surface of said optical member through which the light beam from said light projecting unit is transmitted when traveling from said optical member to said light receiving unit,
• wherein a line normal to the transmission surface is inclined with respect to the principal ray of the transmitted light beam from the transmission surface, 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.