A digital phase measuring interferometer with a frequency-modulated laser diode using the integratedbucket technique is described. The injection current is continuously changed to introduce a time- varying phase difference between the two beams of an unbalanced Twyman-Green interferometer. The intensity of the interference patterns is integrated with a CCD array sensor for intervals of one-quarter period of the fringe. Using the intensity data a microcomputer calculates the phase to be detected. Some experimental results with the interferometer are presented; the rms repeatability obtained was λ/80.
© 1988 Optical Society of America
Jun Chen, Yukihiro Ishii, and Kazumi Murata, "Heterodyne interferometry with a frequency-modulated laser diode," Appl. Opt. 27, 124-128 (1988)