Displacement Measurement Based On Electronic Speckle Pattern Interferometry

One main applications of the speckle measurement method in experimental mechamics is to measure the displacement,strain,vibration and so on.This method can not only proceed non-contact measurement,but also can measure the in-plane or out-plane displacement and the internal or external strain of objects.So it effectively resolves the problems of vibration and transient.In this paper,we introduced the development of speckle measurement technique,and systemly analysed the characters of speckle.Electronic speckle pattem interferometry is the speckle interferometry which is realized by electronics and digital method,and it is a new technique in which the holographic interferometry,computer image processing technique,electronic technique are combined. Here,we introduce the basic theory of measuring displacement by electronic speckle pattern interferometry.We adopted five methods of gray transformation,histogram equalization, medium filter,Butterworth lowpass filter and homomorphism filter,and filtered the electronic speckle pattern with them.We also preprocessed the correlation fringes by refining and shaving.Finally we got the displacement by analysing the correlation fringes.