DOUBLE-FREQUENCY LASER INTERFERENCE METER WHICH MEASURES LINEAR MOVEMENTS Russian patent published in 1997 - IPC

FIELD: instruments. SUBSTANCE: device has lasers 1 and 2 which have different output frequencies, measuring arm which is provided by end corner reflector 3 and optical mixer which is designed as mirrors 4 and 5. In addition device has stable optical arm which length is in range of 0.3-2 m and which is designed as second corner reflector 14 and optical mixer which is designed as mirrors 15 and 16. In addition device has second mixer which is designed as mirrors 6 and 7 and serves for stabilization of difference between frequencies of light flows by means of phase-frequency automatic control units 11. Joined light flows at outputs of mixers are detected by photodetectors 8, 9, 17 which outputs signals to first reverse counter 10 which detects phase signal which correspond to information about both object movement and variation of wavelength of laser beam in air. Signals from photodetectors 9 and 17 are sent to second reverse counter 8 which detects phase signal which corresponds to information only about variation of wavelength of laser beam in air. Both reverse counters 8 and 10 outputs signals which are analyzed by electronic subtraction unit 19. EFFECT: increased functional capabilities. 3 dwg