| 摘要 |
PURPOSE:To reduce the cumulative charge on the inner face as possible, by providing many concaves, convexes or openings on a plane facing an electron beam path. CONSTITUTION:Many concaves 7, convexes or openings are provided on the inner face of a tube 1 for an electron beam path. For example, particles dispersed from a specimen 3 or the residual organic molecule in a tube will adhere to the inner face of the tube 1 of a scan type electron microscope except the concave 7, resulting in formation of an insulative film 8. Then ions produced in the tube 1 or stray electrons will adhere to the film 8, growing up to a cumulative charge, and the superficial charge will flow through the surface of the film 8 to the conductive face of the tube 1 where the film isn't formed in concave 7. When many concaves 7 are provided on the inner face of the tube 1, the path through which the adhered charge will flow to the conductive face at the concave 7 is shortened, resulting in the quick discharging, thereby the cumulative charge onto the inner face is reduced considerably. |
