Indicating DIC Potential Correlation Errors with Optical Modulation Transfer Function

Attempt to indicate the potential correlation errors of DIC method, the modulation transfer function (MTF) test method is proposed in this paper. An Alumnus plate with random pattern on the surface was moved by a linear stage and commercial DIC software was used to calculate the displacement filed while the reference image was taken at focus and the second image set was taken at different field of view. The calculated displacement fields are corrected with a linear function to eliminate unexpected displacement gradient. Meanwhile, the MTF values are also calculated with the same random pattern images. Finally, the MTF values and the slop coefficient of the linear fitting function are related, by this way, once the camera MTFs are known then the possible displacement error can be estimated.