Optical system for recovering optical interference encryption using grating diffraction

This paper presents 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, and 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 the time of decryption, and the random phase information is not needed to recover the image. If we do not have enough information of the ciphertexts, we cannot recover the correct decrypted image. Computer simulations prove its possibility.