Researches On Combined Technology Of4-f System Based Double Random Phase Encoding And Holographic Encryption

The encryption and anti-counterfeit technology has been greatly developed with the technological advances in computers, digital image processing, holography and so on in recent years. The technological advances promote the encryption and anti-counterfeit development and simultaneously provide a high-tech counterfeit technology for counterfeiters. The encryption technology is at the core position in the information security field. The optical information processing technology has the advantages of large capacity, fast speed, parallelism and so on, and provides encryption dimensions, such as phase, wavelength, spatial frequency and so on. Image encryption carried out through using the optical method gradually becomes a research hotspot at home and abroad. The double random phase encryption technology is widely interested and concerned by scholars at home and abroad because of its high securityThe main research works are described as follows:(1) The effects and the importance of the optical information encryption technology in the development of the information society are summarized. The domestic and foreign research and development state of the optical information encryption technology especially the double random phase encoding based encryption technology are reviewed, the disadvantages and present solutions of the double random phase encoding technology are discussed in a classified manner, and then the development and the classification of some basic knowledge and the holographic technology of the optical encryption system referred in this paper are introduced.(2) An experimental optical system for acquiring digital holographic images is designed based on the holographic theory, the holographic interference fringes are digitally recorded and stored by using CCD, and the computer stimulation reappearance of the digital holograms recorded in the experiments was carried out through using a computer by means of MATLAB software, so a better reappearance result is obtained. The double random phase encoding technology based on a4-f system and the basic principle of double random phase encoding technology based on Fresnel transform are introduced in detail, and the computer simulation experiments are carried out through using the holograms acquired in the experiments.(3) Combined with the4-f double random phase encryption system, the images encrypted by the4-f double random phase encryption system are stored in the computed hologram form through utilizing the computed holographic technology, the original encrypted images are extracted through utilizing the diffraction method when the encrypted image stored in the hologram are extracted, encrypted images are obtained through4-f system decryption system, and then the computer stimulation experiments are carried out, so good results are obtained. Stability measurements are carried out against the above encryption method, the influence of the encryption extraction results are analyzed ad discussed from the shear resistance and the noise resistance respectively, and the computer stimulation experiments are carried out, so a case that the method have good shear and noise resistances is confirmed.