Optical Image Coding Technology Based On Diffraction Principle

With the development of modern communication technology,information transmission has become faster and faster,and the security of information has become the focus of attention.The optical encryption system has received a lot of attention due to its simple encryption principle,convenient operation process and high security.In recent years,the introduction of various new optical encryption systems has continuously promoted the development of optical encryption technology.It has a wide range of applications in both civil and military fields.For example,in terms of scientific and technological achievements,trade secrets,military information transmission levels,etc.,the system has a good effect on the encryption of information.This paper first introduces some optical encryption systems proposed in recent years,and then proposes two new optical encryption systems.We perform numerical simulation and security analysis on two encryption systems.The first optical encryption system proposed in this paper is a new image encryption system based on joint transformation correlation principle and ptycholographic iterative engine.When the encryption is performed,the original image can be divided into several parts by using the scanning movement of the probe.Each part is encrypted by the joint transformation correlation technology,and the ciphertexts are finally transmitted in the form of many encrypted images.The receiver uses the working principle of the joint transform correlator to decrypt and reconstructs the image by using the ptycholographic iterative engine,which can integrate multiple images with less information into one high-precision decrypted image.The second encryption system is an optical image encryption system based on grating diffraction imaging and interference superposition principle.When the encryption is performed,an image is encrypted into several ciphertexts by vector superposition,and a random phase is added to each ciphertext to prevent the generation of contours in decryption.During the decryption process,the nature of the grating diffraction in the 4f system would be used,then all the ciphertexts would be superimposed on the same position at the output plane,so that an accurate decrypted image can be obtained.Since the random phase is especially processed during encryption,only the complete information of the ciphertexts needs to be known at thetime of decryption,and the random phase information is not needed to recover the image.If we don't have enough information of the ciphertexts,we can't recover the correct decrypted image.Both the encryption systems can effectively encrypt an image into an irregular noise image and restore it to the original image by the decryption method proposed in this paper.At the same time,the security of the two encryption systems is analyzed by numerical simulation,and their security is verified.