A method is proposed for multiple-image encryption based on optical scanning holography (OSH) using a random phase mask (RPM) and orthogonal compressive sensing (CS). It can destroy the linearity of the traditional OSH system and possess a superior security. On the one hand, images are preferentially preprocessed by utilizing the orthogonal CS to provide a single-layer section for OSH. Therefore, the defocus noise as well as information leakage can be controlled effectively in decryption. On the other hand, each image can be extracted separately without the others’ contents. In addition, the use of RPM can bring about a more ulterior distribution to the cyphertext, which may be better than the case without the RPM. The use of orthogonal modulation matrices and RPM can provide the additional key spaces to guarantee the security of this holography cryptosystem. Simulations and discussions are also made on the cyphertext characteristics as well as the ability of resisting occlusive attack.
In this paper, a color holographic display system based on the effective utilization of the spatial light modulator (SLM) is proposed. Color reconstruction is achieved by using a single SLM. The effective viewing area of three color reconstructed images is analyzed based on the geometrical optics principle and the holographic diffraction theory. Then the effective holograms of three colors are calculated based on the calculation of the effective area of the SLM. When three color parallel light sources are used to illuminate the SLM, color chromatic aberration is compensated by adjusting the blazing grating that loaded on the SLM. At last, three color reconstructed images can be coincided in the same position with a fast speed. The experimental results verify the feasibility of the proposed system.
A method is proposed for color image encryption by using optical scanning holography together with orthogonal compressive sensing, which can provide distinct keys to different channels of color image, along with synchronous encryption. The theoretical demonstration of orthogonal compressive sensing is prioritized to be narrated, which can produce a preprocessed measurement array for the subsequent sampling. The orthogonal basis matrices may provide an additional key space to guarantee the security of this cryptosystem, and the uncertainty of key is used to make a further illustration. The simulations and discussions are also made on the cyphertext characteristics, the robustness of resisting occlusive attack and some other parameters.