| 摘要 |
PROBLEM TO BE SOLVED: To effectively preventing first noise light or second noise light, or first noise light and second noise light from being made incident on a photoreceptor and to make it possible to operate precise optical communication by properly setting a form of a polarizing beam splitter when operating two-way spatial optical communication by projecting and receiving light flux via a polarizing beam splitter. SOLUTION: An optical axis 6 of a projecting lens 2 and that an optical axis 7 of a light receiving lens 4 are made perpendicular to each other, and a polarizing beam splitter 5 is arranged at their intersectional position. The polarizing beam splitter 5 is comprised of a light incident plane 12 and a square pole shape of which a side face 10 is a parallelogram and an upper face 11a and a bottom face 11b are a rectangle or a square. A light projecting/receiving face 9a is tilted to a polarized light separating face 5a, and the polarized light separating face 5a is tilted to a plane orthogonal to a projecting/receiving optical axis 8 of the projecting light. And reflection light from the projecting/ receiving light face 9a of the polarized light beam splitter 5 is guided outside of an effective light receiving face of a light receiving element 3, and cross-talk is prevented in advance. |
