The Optical Encryption Technology Based On Fractional Fourier Transform

Optical information processing(OIP) combines the characteristic of having large-capability, high-speed, parallelism and configuration. The most important thing is that the information can be hided in many parameter such as phase, spatial frequency. So it is an effective method of optical image security.A new method of hiding images based on fractional Fourier transform (FRT) is presented. With this method, the FRT of several images with different fractional orders are recorded on one plate. And another Fractional Fourier Transform accomplishes the hiding after adding the phase encoding. In order to reconstruct the encoded images, several FRT with certain orders and particular phase encoding are needed. However, with the additional degrees of freedom provided by the fractional Fourier transform, the numbers of security keys can be increased. That makes the encrypted images more difficult to be decrypted even by an authorized person. The validity and feasibility of this method is proved though computer simulation.The research product has wide application and prospect in optical encryption and security verification.