Research On Incoherent Optical Image Encryption Based On Coded Aperture Correlation Holography

Optical image encryption has been widely used in the field of information security because it can process a large amount of data,has more optical physical parameters,high degree of freedom of design,and can be realized in physical experiments.Conventional coherent optical image encryption devices are complex and sensitive to alignment,and coherent pseudo noise exists in decrypted images,which requires recording and processing the phase and amplitude of encrypted images,which increases the difficulty of data storage and transmission.Compared with coherent optical image encryption technology,incoherent optical image encryption technology uses incoherent light source illumination,only involves the processing of image intensity signal,has the advantages of relatively simple encryption system,convenient information storage and transmission.However,the current incoherent image encryption systems are more complex,and the image reconstruction quality of some encryption systems needs to be improved.In this thesis,Lensless Interferenceless Coded Aperture Correlation Holography(LICOACH)is introduced into the field of incoherent optical image encryption,and to carry out systematic theoretical analysis,numerical simulation and experimental verification.Specific research contents and main innovations are as follows:(1)An incoherent image encryption method based on LI-COACH is proposed.Using LI-COACH as the encryption system for this method,the experimental setup is particularly simple,,consisting of monochromatic LED,Coded Phase Mask(CPM)and the image sensor.By increasing the number of CPMS and adopting adaptive phase filter reconstruction algorithm,the quality of reconstructed images can be improved.This method only deals with intensity signals and avoids the disadvantage of complex value information processing required by coherent optical encryption technology.Through the analysis of simulation results and optical experiments,this method realizes the incoherent image optical encryption device with simple system and high image reconstruction quality.(2)An incoherent multi-image encryption method based on LI-COACH and integer lifting wavelet transform is proposed.The method is based on the incoherent optical image encryption based on LI-COACH,and the integer lifting wavelet transform is used to extract the low frequency information of multiple images,so as to synthesize one image for encryption.The original image information can be reconstructed lossless during decryption.Simulation results show that this method can realize incoherent multi-image encryption,and has the advantages of simple encryption system,excellent reconstruction quality and high encryption efficiency.(3)An incoherent multi-channel multi-image encryption method based on LICOACH is proposed.In order to ensure that the Point Spread Hologram(PSH)of each optical path is different,and to reduce cross-talk noise between channels,the improved CPMS amplitude distribution is used to design multiple CPMS with low correlation.Based on the low correlation of PSH,multiple PSH images are synthesized into one image,so as to realize the incoherent multi-image encryption device of single exposure and one-time recording.In conclusion,incoherent optical image encryption based on coded aperture correlation holography is studied in this thesis,which further enriches the application of LI-COACH and provides a new perspective for optical information security.