On a High Resolution Laser Interferometer and Velocity Measurement Utilizing the Phase Encoding System
using an absolute encoding technique which is referred to as the phase encoding method. The system becomes immune from the error caused by mechanical, optical and/or electrical noise. The analysis and experiments indicate that the combination of 6 bit A-D converters and 4 kbyte ROM is enough to obtain 5 nm resolution. A circuit scheme to provide with the velocity information in analogue voltage is also presented for the convenience of constructing servo-systems. As the measuring interval of the system varies according to the object speed, the method is applicable to a system where the object speed varies widely.