A Basic Study Of Phase Calculation In Phase Shifted Digital Speckle Pattern Interferometry

Speckle interference metrology is the popular task in the optical measuring mechanics field, and attracting domestic or oversea scholar in optics, mechanics, etc. field owing to its nondestructive, whole-field, real time characteristic. Image manipulation, unwrapping of wrapped phase, calculation speed and precision are still the mainstream study direction due to amounts of speckle noise. Based on that, this paper studies phase shifted digital speckle fundamentally, which has better precision in Speckle interference metrology.Based on the analysis and research of much technology and literatures concerned, this paper aims at the phase measurement in phase shifted digital speckle.Two primarily methods of deriving wrapped phase, i.e. phase-of-difference and difference-of-phase, are compared. Conclusion is achieved by computer simulated speckle.The influence of different averaging kernel, averaging times and aperture size bringing to wrapped phase is studied through simulated speckle program. The result is got through the comparison of Standard Deviation of wrapped phase, which is calculated in different conditions above-mentioned, with the input known wrapped phase. The phase error caused by the different random phase before and after deformation is analyzed with speckle statistics characteristics in the paper.A novel phase measurement method by use of the phase variation of the object self and the phase-shifting technique is proposed, and then phase variation at different time is attained. The out-of-plane tilting speckle interferogram is computer-simulated and the RMS phase error between the calculated phase in this paper method and the input known phase is calculated to verify the feasibility.Combined with the available laboratory conditions, wrapped phase of diffused object subjecting out of plane displacement is measured employingphase shifted digital speckle interference system.