A Computer-Operated Following Ellipsometer

This paper describes the construction and performance of a computer-operated following ellipsometer. By modifying a conventional ellipsometer and operating it with a process control computer, the polarizer and analyzer null positions can he located in about one second with a resolution of 0.01 degrees . This instrument has been used successfully for in situ studies of the buildup and removal of thin anodic oxide films. As the growth of a film is monitored, the computer also plots the null positions of an X-Y recorder and stores all the experimental data for later printing, punching on cards, or replotting along with theoretical curves.