| 摘要 |
PURPOSE:To interrupt harmful light from the background other than the object by providing light reception elements of an image-forming optical system of passive type on the object side from first and second reflection surfaces. CONSTITUTION:First reflection surfaces 3 and 4 are provided so that light a, a passing through image-forming 1 and 2 in the direction to the object is totally reflected toward a second reflection surface 5 and 6 (formed by depositing metal on a prism). The reflection surfaces 5 and 6 are provided to totally reflect the light a, a in the direction to the reflection surfaces 3 and 4 toward the object. Light reception elements 7 and 8 are provided between the lenses 1 and 2. As a result, the light a, a is bent in a U shape by the reflection surfaces 3 and 4 and 5 and 6, reaches the elements 7 and 8, thus forming an object image. The object distance is detected according to the relative position relationship of the object image on the elements 7 and 8. No light entering the elements 7 and 8 directly from the lenses 1 and 2 exists. Also, although it is considered that harmful light b, b', c, and c' entering obliquely exists, it does not reach the elements 7 and 8. |
