METHOD OF DETECTING CHANGES IN ORDER OF INTERFERENCE AND INTERFEROMETER Russian patent published in 1994 - IPC

FIELD: measurement technology. SUBSTANCE: additional arm of interferometer is formed in white color and entire part of changes in optical difference of code is detected from the position of achromatic band, which tracks jumps of order of interference. Light beam of monochromatic radiation source 1 and light beam of while color source 2, passed through the dishes of dish unit 10, where tested matter is located, diffract on narrow slots of diaphragm 18 and are collected by lens 20 in focal plane to form interference pattern. Optical length may be changed periodically by means of modulator 9. Photoconverters 22, 25 and 29 convert interference pattern into electric signals, which have to be processed by electronic circuit. The circuit calculates value of changes in path-length difference. EFFECT: improved reliability of measurements. 2 cl, 6 dwg