Digital speckle correlation method based on phase vortices

A new digital speckle correlation method (DSCM) based on phase vortices is proposed in this paper. The complex signal is reconstructed by a Laguerre-Gauss filter applied to the original speckle pattern. Moreover, the pseudophase distribution is obtained. Each phase vortex position is then located, and its topology charge of +1 or −1 is used to replace the values of the original elements in the pseudophase matrix, in which other elements occupy with zeros. Finally, two sparse matrices representing the speckle field before and after displacement are constructed, respectively. Using these two sparse matrices, correlated calculation is conducted. The results show that this method has the same precision as the traditional subpixel DSCM, while its resumption time is only one-tenth of that of the latter. It is also strongly robust to immune noise.