| 摘要 |
PURPOSE:To perform high efficient detection of an index beam signal, by providing a beam collector plate, having a wave length changing function partially of light in an approximate range of ultraviolet rays, converting into light in a wave length range of high light receiving sensitivity of a photodiode and supplying the light through the beam collector plate. CONSTITUTION:A photodiode 20 is secured to an index light incident surface 16 of a beam collector plate 12 by a transparent material 21 of epoxy resin and the like. A facing side and four side end faces of the beam collector plate 12 are formed to reflective surfaces for increasing a degree of collecting light. The photodiode 20 is provided with intrinsic semiconductor pellets 23, 24, formed with a P type anode area P and N type cathode area N by interposing a common cathode electrode 22, further reflection preventive and protective films 25, 26 are applied on the pellets to form anode electrodes 27, 28. The first light receiving surface 29 of this diode 20 directly catches index light, while the second light receiving surface 30 receives light from the beam collector plate 12 through the transparent material 21. In this construction, detection efficiency of an index light signal can be improved. |
