结合分数傅里叶变换及菲涅耳变换，在光学图像加密系统中分别具有多密钥性和无透镜性的优点，提出了基于分频域和菲涅耳域的光学图像加密方法。基于分数傅里叶变换的光学加密系统，引入菲涅耳变换及全息技术，使原有的加密系统在不增加光学元件的基础上提高了系统的安全性。理论分析和计算机仿真模拟证明了这种方法的可行性。

A method of the optical image encryption based on the frequency splitting domain and Fresnel domain is proposed, after the analysis of the fractional Fourier transform and Fresnel transform, by synthesizing the advantages of multi keys and lensless feature of the fractional Fourier transform and Fresnel transform in the optical image encryption system. The Fresnel transform and hologram technique are introduced into the optical encryption system with the fractional Fourier transform to improve the security of the original encryption system without increasing other optical elements. The theoretical analysis and computer simulation indicate that the method is feasible.