Sinusoidal phase modulating laser diode interferometer for on-machine surface profile measurement

A disturbance-free sinusoidal phase modulating laser diode interferometer using an accelerated integrating-buckets processing system is described. Several techniques make it suitable for use in on-machine measurements: the charge-coupled device (CCD)-based additive operation on integrating buckets shares the burden of data processing imposed on the computer to shorten the measurement time; the use of high-speed shutter function of the CCD camera enables each bucket to be collected without disturbance, while the interference signal’s stability is enhanced with the feedback control during the entire data-collecting time; by using a dedicated waveform generator, the phase modulating system is more compact and the modulating signal matches the CCD camera’s exposure time easily and exactly. A surface profile measurement on a diamond-turned aluminum disk is demonstrated to evaluate the performance of this system