| 摘要 |
PURPOSE:To make the photodetection surface of a photodetector optional shape and optional size by using mirror surfaces as respective surfaces of four prisms except incidence surfaces and projection surfaces. CONSTITUTION:The prisms 7a-7d are arranged in contact symmetrically about the incidence optical axis 2 of an objective lens 1. Surfaces of the prisms 7a-7d except prism incidence surfaces 11a-11d and prism projection surfaces 13a-13d are all made into mirror surfaces by vapor-depositing aluminum. A light beam forming a subject image 10 is split into four by the prism incidence surfaces 11a-11d and projected from prism projection surfaces 13a-13d with a little decrease in the quantity of light. Those beams are converted on photodetection surfaces of the photodetectors 3a-3d through condenser lenses 8a-8d. |
