A new optical image encryption method based on multi-beams interference and vector composition

• An encryption technique based on multi-beams interference is proposed.
• The original image is encoded into n phase only masks by vector composition.
• There is some difficulty in getting the n masks, and we resolve it.
• We also resolve the contour problem happened in other interference based methods.
• Computer simulations are presented to verify the validity of the proposed method.

In this paper, a new method for optical image encryption based on multi-beams interference principle and vector composition is proposed. In this encryption, the original image is encoded into n−1 phase only masks which are regarded as the keys of the encryption system and a ciphertext according to multi-beams interference principle and vector composition. In decryption process, n beams of parallel incident light illuminate at the phase only masks and the ciphertext, and we can obtain the decrypted image at output plane after Fourier transforms. The security of the proposed method is discussed, finding that no decrypted image can be obtained only when all the keys used are right. Furthermore, the keys can be stored separately resulting in improving the security of encryption system. Computer simulation results are presented to verify the validity of the proposed method.