Analysis Of Influencing Factors Of Speckleshearing Phase-shifting Pattern Interferometric Systerm

Electronic speckle shearing pattern interferometry (ESSPI) is a quantitative method of measuring objective surface strain field directly, which is widely used in strain field-measurement and Nondestructive testing (NDT). In this thesis, the whole System for the composition of ESSPI is presented elaborately. Furthermore, the influence on the measurement resolution, measurement accuracy, measuring range and the contrast of stripe of the measurement system of the lighting system, shearing system, phase-shifting system and loading system of ESSPI were analyzed in detail separately.Shear quantity, which determine the measuring sensitivity and range, is the most important index of the system. So influence factors and measurement method of shear quantity is analyzed at length. The measurement accuracy of the system is largely determined by the phase-shifting accuracy, of which, thus, the precision and error of the two control mode is nicely calculated.This thesis mainly focuses on following aspects:1 The thesis applies four methods, which are equation, Moiréfringe technique, correlation method and imaging method, to measure the shear quantity. And measuring range of each method is summarized.2 The precision of both closed-loop control and open-loop control is simulated, and experiments were carried out to verify the simulate results.3 The influence on the precision of phase-shifting caused by linearity error is analyzed theoretically, and a method of eliminating the error is put forward, of which the validity is verified both by simulation and experiment.4. The influence of the wavelength, spectral width, wave-front, polarization degree and in-homogeneity of the light source on the system is analyzed elaborately.