Transformed phase mask in a hybrid joint transform correlator for security verification

The hybrid optical-digital joint transform correlator (HJTC) experimental setup was created. The minimum focal length of a Fourier lens in the joint Fourier transform processor (JFTP) was found. The procedure of the transformed phase mask (PM) identification in the HJTC was represented. A several modifications of the setup with different effective focal length of the JFTP were used for investigations of transformed PMs. The peak-to-noise ratio (PNR) for each correlation peak in the first diffraction order of the output correlation signal was selected as the objective criterion of the transformed PM identification performance. The performance of the transformed PMs identification in the HJTC was studied. The dependencies PNR versus effective focal length of a JFTP were analyzed. The influence of the CCD-camera recording aperture relative dimensions on degradation of correlation peaks was studied.