Direct phase modulating laser diode interferometer for in-process measurement using sinusoidal signal synchronized with the CCD camera's exposure time

摘要

A disturbance-free sinusoidal phase modulating laser diode interferometer using integrating bucket method is described. Several techniques make it suitable for use in the in-process measurement: the charge-coupled device (CCD) based additive operation on integrating-buckets shares the burden of data processing imposed on the computer; the modulating signal is matched with the CCD camera's exposure time easily and exactly by using a dedicated waveform generator; the use of high speed shutter function of the CCD camera enables each bucket collection to be insensitive to the noise, while the interference signal's stability is enhanced with the feedback control during entire measurement time. A surface profile measurement on a diamond-turned aluminum disk was demonstrated to evaluate the performance of this system.