A digital phase measuring interferometer with a frequency-modulated laser diode using the integrated-bucket 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
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