Spatial fringe analysis method based on Fourier transform technology by using only two speckle patterns for electronic speckle pattern interferometry

Abstract

Electronic speckle pattern interferometry with high resolution power based on Fourier transform using only two speckle patterns is proposed by using the new optical system. Furthermore, the occurrence process of unresolved speckle in speckle pattern which is grabbed by the optical system is also discussed. The condition that can avoid the occurrence of unresolved speckles for the fringe analysis is proposed. In experiments, the measuring accuracy of the method is improved in the measurement of out-of-plane deformation by rotating a flat plane using the shift of the information in frequency domain. It is confirmed that the accuracy of the method is higher than 1/130 wavelength of light source and that the out-of-plane deformation with a concave phase distribution can be also measured.