| 摘要 |
PURPOSE:To enable a photoelectric tube to be placed near the subject so as to achieve increased optical efficiency by using a tub-like photoelectron-emitting screen the cross section of which is a circular arc the curvature center of which is located outside the outer tube and applying a light-shielding medium to the area of the outer tube other than its window to which a light-scattering medium is applied. CONSTITUTION:A cathode 52 consists of a tub-like electrode which constitutes a circular arc which has r diameter and the curvature center of which is located outside an outer tube 51. The inner surface 501 of the window 50 of the outer tube 51 upon which light becomes incident upon is formed by delustered glass. An anode 53 consists of a rod so that an adequate amount of light reaches the cathode 52. In order to prevent any decrease in the S/N ratio which might be caused by light traveling through the area 51 other than the window 50, the area 51 is shielded from light by chromium or similar material. Accordingly, it is possible to produce a photoelectric tube having good light-receiving efficiency and stable characteristics. |
