| 摘要 |
PURPOSE:To raise the focusing efficiency of light by focusing a light signal on a photoelectric conversion element through a concave mirror provided on the outside of a window. CONSTITUTION:The index photodetection window 20 provided on the funnel wall is provided with the concave mirror 101 on its outside, and the photosensor 11 is provided at the image-focusing portion of the fluorescent screen 9. Thus, all light coming into the opening of the concave mirror 101 is made to take a part in its photoelectric conversion, so that a solid photoelectric conversion element such as PIN diode element can be used without the need for expensive photoelectric multiplier tube, etc., for the photosensor 11. |
