| 摘要 |
PURPOSE:To enable observation of a feeble light image in a magnification manner without the influence of thermal noise thereon by limiting the effective area of an photoelectric surface smaller than an image formation surface, thereby forcusing the image on the specified image formation surface while accelerating and magnifying emmitted electrons. CONSTITUTION:A pair of convex lens 21, 22 are arranged in front of an image tube (magnification tube) 30 and a concave lens 23 between the lens 21, 22. In this manner an optical system 20 is provided. The magnification ratio is set 1:1 and the image of a small substance 1 is focused on a photoelectric surface 4 narrow in its effective area. An acceleration electrode 31 is arranged in front of the surface 4 such that a part of which covers the front face of the surface 4 widely and at the center of the electrode 31, an aperture 32 is formed so that it limits the effective area of the surface 4. A magnification collection coil 10 forms an electronic image that is, for example, magnified 40 times in front of a microchannel plate (MCP)6 which has an electronic magnification function in common with prior arts. A TV camera 9 serves to pick up the image of a substance 1 formed on a fluorescent screen 7. It is thus possible to observe a feeble light image from a dark substance while magnifying same without influence thereon of thermal noise.
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