Recently, CCD camera has been more and more used in the electron microscopy particularly for electron crystallography . Use of CCD camera in this field as a recording medium possesses many significant advantages over conventional photographic films. A CCD camera has a very high dynamic range (reliable) and produces images directly in digital form which can be conveniently processed and transferred. We have initiated a program to obtain crystal structural information of plate-like materials by processing electron diffraction data from a CCD detector. As part of our program, we have developed a complete and routine procedure to convert images to diffraction data (h, k, l’s and intensities).
Figure 1 is a schematic representation of the procedure. Images are initially obtained using a 1024×1024 Gatan CCD camera (model 794) which was attached to JEM-2000EX electron microscope. The collection of the images is controlled by a MAC computer which also stores the data and allows the data to be viewed. Then, the digitized electron diffraction patterns are transferred to a Sun station computer where, using Khoros software, the CCD images are processed. The Khoros system is a very complete image analysis and image processing software developed by University of New Mexico .