Measurement of absolute displacement by a double-modulation technique based on a Michelson interferometer.
A novel method is presented for of measuring absolute displacement with a synthesized wavelength interferometer. The optical phase of the interferometer is simultaneously modulated with a frequency-modulated laser diode and optical path-length difference. The error signal originating from the intensity modulation of the source is eliminated by a signal processing circuit. In addition, a lock-in technique is used to demodulate the envelope of the interferometric signal. The displacement signal is derived by the self-mixing technique.
Chang
L W
LW
Institute of Optical Sciences, National Central University, Chung-Li, Taiwan.
Chien
P Y
PY
Lee
C T
CT