Frequency shifted laser interferometer for measuring distance - has two optical paths whose ends have detecting and measuring circuit

摘要

The laser interferometer has two optical paths transmitting partial laser radiation. The path difference 0 constitutes the distance to be measured, and at whose ends, the exiting radiation is fed to a detecting and measuring circuit. The laser is shifted in frequency so the exiting rays from the measuring interferometer set up an oscillating signal by interfering on a single photodetector of the detection and measurement circuit. The total continuous phase X per frequency oscillation is proportional to the path difference. A calibration interferometer is provided with two optical paths whose path difference has a knwon value C. The exiting rays set up another oscillating signal by interfering on another similar photo detector whose total continuous by phase per frequency shift is defined in the detecting and measuring circuit so the distance D = C.X/Y.