利用随机相位板复用提出了一种基于干涉原理的光学多二值图像加密系统。该系统加密过程采用数字方法，解密过程既可以采用数字方法也可以采用光学方法。利用该方法可将多幅图像信息解析地隐藏于两个纯相位板中。解密时，通过分束镜将两个随机相位板的衍射场进行相干叠加形成干涉场，利用专用密钥对此干涉场进行调制，即可在输出平面上恢复出与该专用密钥对应的原始图像，此图像可以采用CCD等图像传感器件直接记录。该方法加密过程无需迭代，非常省时，且解密系统易于物理实现。利用相关系数评估了系统的加密容量，计算机模拟结果证实了该方法的有效性。

A system for interference-based optical multiple binary image encryption by random phase mask multiplexing is proposed. The encryption process is realized digitally and the decryption process can be completed optically or digitally. Multiple binary images can be analytically hidden into two phase only masks (POMs). For decryption, the diffraction filed of the two POMs are superposed by utilizing the beam splitters to form a complex field, then the complex field is further modulated by the private key, as a result of which the original plaintext assosicated with the private key is retrieved. The regenerated image can be directly recorded by CCD camera. The encryption algorithm for this new method is quite simple and does not need iterative encoding. In addition, the decryption system is easy to be realized physically. The multiplexing capacity is analyzed through the correlation coefficient. Computer simulation results confirm the validity of the proposal.