A Diffraction Adapter for the Electron Microscope

Abstract

An adapter has been developed which allows a conventional electron microscope to be used interchangeably as an electron diffraction camera or an electron microscope. The adapter comprises a unit which takes the place of the projection lens unit of the microscope, and includes a newly designed microscope projection lens, a specimen holder, and a focusing lens. To transform the instrument from a microscope to a diffraction camera (or vice versa) it is necessary only to transfer the specimen from the regular object chamber to the adapter. Diffraction patterns may be obtained by either reflection or transmission. As a result of the excellent reproducibility of voltages and currents from the regulated power supplies used in the electron microscope, the diffraction camera holds its calibration to within 0.1 percent over long periods. Using a calibration determined by measurements of gold patterns, lattice spacings of a number of common materials were determined and found to agree with x‐ray values to within 0.5 percent.