An Automated Electron Microprobe System

Abstract

An automated- electron microprobe system using an on-line 8,000 word minicomputer has been designed. The general principles and need for such a system is discussed. The microprobe-computer interface hardware consists of computer addressable axis positioners, scalers, timer and a digital to analog converter. The axis positioners are used to position the spectrometers and specimen stage, whereas the digital to analog converter is used to position the electron beam in a 1000 × 1000 point matrix. The digital to analog converter is also used to drive a X-Y recorder for computer plotting of calibration curves, pulse amplitude distributions, X-ray line profiles and wavelength scans. System software is written in the interactive CLASS language which was designed specifically for laboratory instrument control. The language permits large computer programs to be chained through a minicomputer while passing variables from one function to the next. The operating software consists of automatic peak location, sequencing of data collection, statistical analysis of data, and correction of data for fluorescence, absorption and atomic number effects. An automated quantitative analysis of several copper-gold alloys and a computerized test for specimen homogeneity is described to demonstrate system operation. Future automation considerations are also discussed.