Synchronous Shift The Proposition Vibration Interference

Phase-shifting interferometry (PSI) is a highly sensitive method used for non-contact precision optical testing. However, the external vibrations are often the dominant error sources in phase-shifting interferometers. At present, the anti-vibration technology in interferometry is one of the primary researching problems in optical interferometry field. The simultaneous phase-shifting interferometry has become a new direction in vibration-resistance phase measurement, because it can eliminated the effects of vibration from measurement by creating three or four separate phase shifted interferograms simultaneously by spatial phase-shifting method. This technology is a real-time anti-vibration method.The principle of three different simultaneous phase-shifting means is derived by Jones Matrix method. After discussing the advantage and the disadvantage among the three means, the means with diffraction grating splitter and polarization phase-shifting is selected to establish the experiment system. In this measuring system, a 2-dimentional grating is applied. By the grating, 4 diffracted beams of (±1, ±1) orders are formed for the same diffracting efficiency. Each passes one of four polarizing plates respectively, whose polarization directions are different with 45 degree in turn. So four interference patterns which have 90 degree phase-shifting intervals are obtained simultaneously, and the four patterns can be captured by only one CCD camera. With the set-up of the simultaneous phase-shifting interferometry, the interferograms are digitized and the profile of the test surface is thus derived by use of 4-bucket algorithm. In the end of this paper, the system error sources are analyzed wholly. Experiments are performed to verify the applicable and effective of this anti-vibration technology.