Speckle photography surface displacement algorithm based on Fourier transform phases

The invention discloses a speckle photography surface displacement algorithm based on Fourier transform phases. Fourier transform of digital speckle patterns of an object before and after displacement is respectively carried out, Fourier transform results are divided to acquire a two-dimensional complex number, a phase angle of the two-dimensional complex number is calculated, cosine operation of the phase angle is carried out to acquire an equivalent young's interference pattern, Fourier transform of the young's interference pattern is carried out, coordinates of maximum values of a Fourier transform power spectrum except zero frequency are queried, surface displacement can be acquired, a displacement direction of the object can be determined according to plus or minus of a phase angle gradient, and a derivative algorithm of the algorithm can be utilized to realize sub-pixel displacement calculation. The algorithm solves problems of tedious steps, heavy computation and inconvenient operation and especially s