| 摘要 |
PURPOSE:To obtain a light beam having high directivity by emitting light which deviates from a specified angular range and advances in a light guiding part on a reflection surface to the outside of the light guiding part. CONSTITUTION:The light beam made incident on the light guiding part 50 from a photodetector 51 is reflected in nearly vertical direction on a 1st reflection surface 53. At such a time, a part of the light made incident on the surface 53 at a large angle which exceeds a clitical angle on the surface 53 is emitted to the outside from the surface 53. After the light beam which is reflected from the surface 53 and advances straight is splitted into plural light beams by a branching part, it is reflected on a corresponding 2nd reflection surface 55. It happens that a part of the light made incident at an incident angle which exceeds the critical angle on the surface 55 is emitted to the outside of the light guiding part. The light beam which is reflected on the surface 55 and advances straight is emitted from a light emission part 52. Thus, the light which deviates from the specified angular range and advances in the light guiding part is emitted on the reflection surface to the outside of the light guiding part, so that the directivity is given to the light beam emitted from the light emission part to the outside of the light guiding part. |
