Optical Image Encryption Technology Based On Interference Principle

It is well known that the optical image encryption technology has been rapidly developed over the past decade.Because of its fast and multiple degrees of freedom(such as wavelength and phase),this research field has gradually become the focus of domestic and foreign scholars.Nowadays,with the advancement of Internet technology,information security is facing a big threat,therefore optical image encryption technology has good prospects for its development.Since the double random phase encryption system was put forward by Javidi et al.in 1995,a number of optical encryption methods are emerging after that.In this article,we make a brief introduction about the development of optical image encryption and several classical optical encryption systems,optical image encryption based on interference principle is mainly introduced,and we develop the number of beam and the way of vector composition respectively.In this paper,the principle of double-beam interference is reviewed,and the asymmetric optical cryptosystem based on coherent superposition and equal modulus decomposition is introduced.On this basis,a new optical image cryptosystem based on two-beam coherent superposition and unequal modulus decomposition is analyzed.Then,we introduce the way of vector composition to present a pseudo color image encryption method based on three-beam interference principle and common vector composition.We divide the information of one original gray image into three parts of amplitude information and three parts of phase information.The three parts of amplitude information are encrypted into color ciphertext by tricolor theory,and the others are regarded as the keys.Finally,we generalize the beam to the n-beam,and propose an optical image encryption technique based on n-beam and common vector decomposition,it has wider application range and better security.Based on the multi-beam interference and common vector decomposition,the information of an original image is encoded into n amplitude masks and n phase masks,which are regarded as a ciphertext and many keys.In decryption process,parallel light irradiates the amplitude masks and phase masks,then passes through lens that takes place Fourier transform,and finally we obtain the original image at the output plane after interference.We have carried out numerical simulation for the above new method,computer simulation results verify the correctness and feasibility of these encryption methods.Only when all the keys are correct,the information of the original image can be restored.This method can removes the outline problem of the double beams interference.Meanwhile,we also discuss the security of the proposed method for key errors,ciphertext errors,and adding white Gaussian noise,verify the security of these encryption methods.