| 摘要 |
PURPOSE:To make it possible to detect a light beam securely by reflecting a light beam, projected from a projection part, penetrating a body to be measured by a reflection part, by returning it to the projection part again by way of the same part of the measured body, and by light-branching and supplying it to a photo detection part. CONSTITUTION:A light beam is projected from projection part 13 on measured body 11 after penetrating light-branch part 28 straight, and the light beam having penetrated measured body 11 is caused to strike reflection part 29. Since reflection part 29 reflects the beam accurately in the same direction as its incident direction, the reflected beam penetrates the same part of measured body 11 as the penetrating beam and is divided by light branch part 28 before being led into photo detection part 14. Since projection part 13, photo detection part 14 and light branch part 28 are fixed on the same support part 31, there is no mutual position shift, so that the light beam reaching photo detection part 14 will never shift. |
