Collection and Analysis of Sem and Tem Data Using a Random Access Video Frame Store

Abstract

We have investigated the possibility of using a large random access video frame store (VFS) for the collection, storage and analysis of SEM and TEM data. Here we describe how such a store can be used to enhance the microanalytical facilities in our laboratory, and we show some preliminary results to demonstrate its power. A block diagram of the proposed system is shown in fig. 1. The store is arranged so that data can be collected, displayed and randomly accessed by the computer, all independently and asynchronously. The VFS can be addressed either from an external source or addressing can be software generated, with the computer also controlling the source timing. The computer has access to any part of the VFS and can thus remove, modify and replace any stored data at any time allowing simple processing routines to be performed in real-time, or more complex operations on 'frozen' images. Standard computer peripherals are used for operator interaction for program storeage and for hard-copy recording of graphs and numerical data. Synchronous read and write operations on the VFS allow noise-reduction of TV rate images by time-averaging or recursive filtering. This is of particular advantage over long lime-constant SEM and SAM imaging as it enables one to observe the image continuosly while greatly reducing the effects of 1/f noise. Asynchronous operations enable the VFS to be used for scan-conversion of SEM slow-scan inputs into good quality TV rate images for display and video recording.