| 摘要 |
In an apparatus for measuring an intensity of an electron beam, the electron beam is made incident a fluorescent screen and a part of the incident electron beam is converted into an optical image, and the optical image formed on the fluorescent screen is picked-up by a television camera by a reflection mirror having a central hole and being inclined with respect to a direction into which the optical image is made incident upon the reflection mirror. A part of the electron beam transmitted through the fluorescent screen and passing through the central hole of the reflection mirror is made incident upon a Faraday case, which generates an electric current representing an intensity of the electron beam impinging upon the fluorescent screen. In the transmission type electron microscope, after measuring an intensity of the electron beam impinging upon the fluorescent screen, after removing the fluorescent screen, reflection mirror and Faraday cage from an optical axis, a shutter is opened to expose a photographic film to the electron beam for a time period which provides an optimum exposure on the basis of the measured intensity of the electron beam.
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