ULTRA-HIGH-RESOLUTION HVEM (H-1500) NEWLY CONSTRUCTED AT NIRIM .2. INSTRUMENTATION

Basic specifications and some experimental data of a new ultra-high-resolution HVEM (Hitachi H-1500), with a maximum accelerating voltage of 1300 kV, are described. A lattice fringe image of 0.07 nm is obtained from thin gold film, indicating excellent mechanical and electrical stability of the microscope. Spherical and chromatic aberration coefficients of the objective lens are 1.85 and 3.4 mm, respectively, at 1300 kV; and a theoretical point-to-point resolution, defined by the first-zero point of the contrast transfer function (CTF) curve under the Scherzer condition, is about 0.104 nm. A crystal structure image of silicon, in which each silicon site is observed as a black dot, is successfully obtained and the image agrees fairly with the results of computer simulations based on the above optical parameters.