Fingerprint identification using the directions field

Optical-digital systems dedicated to the identification of fingerprints using the spatial spectrum and the directions field are discussed. For constructing the directions field, the proposed optical configuration uses a coherent correlator with a spatial filter consisting of sectional diffraction gratings. It is shown that the analysis based on the directions field is favoured. It is also shown that in analysing fingerprints using the Fourier-spectrum, it is only the information on the angular spectrum distribution that appears to be essential, whereas the information related to the radial spectrum distribution is abundant.