A video data-acquisition system for quantitative low-energy electron diffraction studies

We have developed an easy to use and inexpensive low-energy electron diffractometer. The system is based on an Apple Macintosh II microcomputer and uses a high-resolution CCD video camera. The video interface is a single plug-in imaging board which digitizes the video signal in real time. No expensive auxiliary video processing devices are required. The system is of moderately high speed. A typical set of 16 IV curves with 125 data points in each curve can be generated from images summed over 16 frames in less than 4 min. Spot profile measurements are also routinely made. A description of the apparatus and the capabilities of the system are presented, illustrated using measurements of the epitaxial growth of bismuth films on III-V semiconductor surfaces.