Low energy electron diffraction apparatus

摘要

1,058,522. Electron beam apparatus. VARIAN ASSOCIATES. Jan. 6, 1965 [Jan. 6, 1964], No. 634/65. Heading H1D. In an electron diffraction apparatus in which the specimen is irradiated with a collimated stream of low-energy electrons, the collimated stream is focused to a small spot on the specimen surface by an electron lens located between the specimen and a luminescent screen for displaying a pattern created by electrons diffracted from the surface of the specimen. The specimen 27 is supported at the centre of curvature of a part-spherical luminescent screen 21 through the centre of which projects a coaxial tubular anode system 38, 39 the ends of the tubes adjacent the specimen acting as a lens. In a modification three tubular coaxial anodes are provided to form an Einzel lens system. The screen 21 and the grids 50, 51 associated with the screen are supported on hollow ceramic tubes containing the leads, Fig. 3 (not shown), and the gun electrodes are supported on further ceramic rods, Fig. 4 (not shown). The specimen is mounted for rotatable, tiltable and vertical and lateral movement by means of a manipulator unit (not shown). The cathode filament 37SP1/SP is cruciform and heated by A.C. supplied to leads on opposite points of the cross.