Design And Reaseach On Optical Phase-shifting Phase Measurement System

Optical phase measurement is a high accuracy phase measuringmethod which is widely used in displacement testing, object distortionand density distribution analysis etc. For the measuring object withnon-regular surface and phase distribution, non-uniform and small change,optical phase measurement can develop it's advantages and fulfill therequirement of non-destructive and non-contact testing, high precisionand automatization. Up to now, some problems remain in the phasemeasurement including: phase measuring theory development,phase-shifting phase measuring system with high precision and goodcapacity from preventing noise, phase-shifting algorithm and how toevaluate the phase measuring error. By theoretic analysis, phase-shifting phase measuring system'sdesign and the corresponding experiment, this paper gives some researchabout the phase-shifting phase measurement including: phase measuringtheory analysis, phase-shifting technique, how to evaluate phasemeasuring error, phase-shifting phase measuring methods of static anddynamic process. In this paper, the main innovative ideas are as following:1. By use of the point of view of holography, a phase-shifting phasemeasuring method of N-steps full period phase-shifting in a period isproposed, which is equal to that of separation and superposition ofcomplex amplitude synchronously, and can be used in the phasemeasurement of the diffracting object by non-plane reference wave.2. A phase shifting phase measuring system is designed, in which thelaser wavelength is used as the measuring standard of length, therelationship between the displacement of PZT and the voltage can bemeasured, the phase-shifting region can be chosen and calibrated, andphase-shifting driver and phase-shifting images recording can becontrolled , and the phase-shifting process can be inspected.3. By use of N-steps full period holographic phase-shifting algorithm, anevaluating phase measuring error method is proposed, and it is proved thephase measurement error is directly proportional to the square of themaximum of phase-shifting error, and is inversely proportional to thephase-shifting step number N. If N is increased, the influence forphase-shifting error and other random factors to phase measuring resultwill be decreased.4. By combining phase-shifting technique with least-squares fittingalgorithm (CPSLSF), a novel method of phase measurement of timesequence of interferograms is proposed, and the experimental resultshows the phase measuring accuracy of the proposed method is the sameas that of the conventional phase-shifting method.