Study On Applications Of Double Random Phase Encrypted Holograms And Joint Transform Correlation In Anti-counterfeit

An experimental study on applications of double random phase encrypted holograms combined with joint transform correlation (JTC) in anti-counterfeit is presented in this paper.Firstly, the principles of double random phase encryption and joint transform correlation are analyzed.Secondly, an optical experimental system is set up for double random phase encryption, holographic recording and detecting with joint transform correlation. The holograms of double random phase encrypted image are recorded in photoresist. Optical JTC and optic-electronic hybrid JTC are applied for both correlation peak and decryption detecting. In optic-electronic hybrid JTC system, the joint transform power spectrum is recorded by charge coupled device (CCD), and the correlation result is obtained by fast Fourier transform in computer rapidly. Several conditions affecting the correlation detecting results in optic JTC and optic-electronic hybrid JTC, such as defocus of recording position of joint transform power spectrum, recording size! of the encrypted image are experimentally studied.Finally, results of correlation detecting with optic JTC andoptic-electronic hybrid JTC for both correlation peak and decryption are given and compared each other. The analysis of the effects of joint transform power spectrum recording defocus and encrypted image recording size on correlation results is given, and the reason of these effects is also analyzed. The influences of the CCD resolution and the discrete Fourier transform characteristic on correlation results are discussed.