| 摘要 |
PURPOSE:To realize an electron ray device to which any contamination is prevented from adhering by forming an iris, which is installed on an electron-ray path, of several thin layers so as to prevent any electron from being scattered by the iris and to make the temperature of the iris to be easily maintained high. CONSTITUTION:The symbols 6A-6B represent circular thin plates stacked on the lower surface of an iris 1, and the symbol 6C represents a circular thin plate stacked on the upper surface of the iris 1. The thin plates 6A-6C are almost concentric with the hole of the iris 1, and also have center holes with larger diameters than that of the hole of the iris 1. In addition, the center hole of the plate 6B is larger than that of the plate 6A. According to the constitution mentioned above, the section of the integrated body consisting of the iris 1 and the plates 6A and 6B has an almost cone-shaped opening, and the section of the integrated body consisting of the iris 1 and the plate 6C also has an almost cone- shaped opening. Here, as a matter of course, it is the iris 1 that functions as a member which restricts electron rays 4. |
