DETECTION OPTICAL DEVICE

摘要

PURPOSE:To enable high-sensitivity body detection and high-accuracy body distance detection by composing a convergence optical device which photodetects the light beams from a body to be detected in a specific plane by using a converging prism which has two cylindrical concave reflecting surfaces. CONSTITUTION:The converging prism P has the cylindrical concave reflecting surfaces 22 and 23 for convergence in the surface perpendicular to a plane and a photodetecting element 27 which is arranged on the focal plane determined by those reflecting surfaces. Then luminous flux which is made incident on the prism P after being reflected by the reflecting surface 22 is reflected by a reflecting surface 23 and photodetected by the element 27 on the focal plane 24. Here, the center of curvature of the reflecting surface 22 is on the opposite side of the reflecting area of the reflection area of the reflecting surface 22 about the reflection area of the reflecting surface 23 and the center of curvature of the reflecting surface 23 is distant from the incidence surface 21 of the prism about the reflection area of the reflecting surface 23. Consequently, the two cylindrical concave surfaces 22 and 23 are combined to converge reflected light from the body, the comatic aberration is reduced, and the converged spot size is reducible, so the detection accuracy of the body distance can be improved.