Joint transform correlator with fractional Fourier transform

The configuration of the nonconventional joint transform correlator provides an optical implementantion of the fractional correlation. The fractional correlation has the advantages over the conventional correlation such as a spectral distribution with no high peak and a very sharp correlation distribution. At the center of the correlation output plane, the fractional correlation gives the same value as the conventional correlation, though it is not shift-invariant but partially shift-variant. (C) 2002 Elsevier Science B.V. All rights reserved.