| 摘要 |
PURPOSE:To enable a measuring sample to prevent the charge up of an electron beam generation system by a released electron beam, by providing a device which inserts a shielding body between an electron gun and a measuring sample to shield electron beams when no measurement is done. CONSTITUTION:An electron beam 2 is made to irradiate a measuring sample 8 only for a measuring time and intercepted and absorbed by a metal plate 5 to be escaped to the ground 7 through a wire 6 when no measurement is done. With such an arrangement, the measuring sample 8 is allowed to receive the electron beam 2 for a short time only during the measurement, hence freed from the fear of being charged up. As there is no need for curving the electron beam 2, any of the electron beam 2 will not hit a blanking aperture 4 or the like, which by no means causes a charge up in a beam generation system. Since the metal plate 5 is used as shielding body and connected to the ground, no excess electric field is formed in the perimeter thereof. |
