In this paper, we propose an asymmetric cryptosystem based on dynamic foveated imaging and bidimensional empirical mode decomposition (BEMD). Firstly, a novel dynamic foveated imaging algorithm is developed to transform a plaintext image to a globally ambiguous and locally clear image. Then, the image is passed through a phase-truncated Fourier transform system to generate a white noise image. The resulting image is encoded using BEMD to produce an encrypted image. The proposed cryptosystem offers two distinct decryption methods, allowing the receiver to obtain a decrypted image from a specific frame or a combination of frames, depending on the unique keys. This encryption scheme significantly expands the key space and strengthens the system’s anti-iterative attack capability. Numerical simulation results demonstrate the effectiveness, security and robustness of the proposed cryptosystem.

Optical holographic encryption (OHE) has been extensively researched in the field of information security due to its parallel and multi-dimensional characteristics. However, although some progress in OHE has been made in recent years, inherent security flaws resulting from the robust nature of holograms persist. In this study, we propose a multilevel holographic encryption method based on the Tiger Amulet (TA) concept. Compared with the normal OHE, our method employs two ciphertexts. It strategically utilizes the low-level plaintext as intentional deceptive content to confound the potential eavesdroppers. Furthermore, we ingeniously exploit the hologram’s robustness in reverse, thereby establishing an additional protection mechanism to enhance the security of the middle-level plaintext. Leveraging the TA concept, the high-level plaintext can only be decrypted when two matched ciphertexts are combined and collimated. The TA based decryption mechanism enhances the security and sensitivity deciphering high-level plaintext. Benefiting from the security mechanisms above, our proposed method demonstrates promising applicability across diverse scenarios and holds the potential to redefine the landscape of multilevel OHE design.

Multispectral imaging systems enable the simultaneous acquisition of spatial and multispectral information about a target, thereby improving the capability of all-weather autonomous spacecraft operations for sensing measurements and condition identification. This paper reports designing and constructing a common-aperture multispectral imaging system (CAMIS) that can simultaneously obtain ultraviolet, visible, mid-wave, and long-wave infrared wavebands. Such a system can simultaneously realize distant stars' navigation and multispectral detection. An experimental setup was constructed to verify the basic principles of the device. The device is used to image an optical-resolution target and a pinhole. The results indicated that the system could perform celestial navigation in the visible waveband and image objects well in multiple wavebands, thereby realizing the integration of deep-space navigation and detection.

Free space optical communication (FSOC) is a potential technology for next generation communication. To reduce the construction cost for the receiving node in FSOC network, in this paper, we propose an ultrawide coverage (UC) receiver based on compound eye structure. The UC receiver consists of nine compound eye channels arranged in 3 rows multiply 3 columns. All the channels in the receiver use the same signal collecting system (SCS). Among the channels, the difference between the central channel and the non-central channel is that each non-central channel is equipped with a field of view (FOV) transform system to change the cover region and expend the coverage. Simulation results of coverage indicate that the effective coverage of the proposed system is 2.433sr, which is about 19.36% of the whole spherical space. Besides, when it works outside the presupposed blind distance, no blind zone coverage has achieved and the overlap rate of coverage is only 3.93%. Compared with the normal receiver with the same parameter, the coverage of the proposed receiver is increased by 57.6%. Moreover, performance simulation results show that, the average Bit Error Ratio (BER) of the proposed receiver is better than 2.47 x 10-6 in strong turbulence, which is enough to have a stable communication link. The new designed UC receiver has a great potential as an airborne suspended receiving node to establish FSOC network and may paves a new way for the design of FSOC receiver with an ultrawide coverage.

Off-axis reflective zoom imaging optical system has a wide range of applications in the field of photoelectric detection because of its advantages of chromatic aberration-free, broad-spectrum imaging. The existing off-axis reflective zoom imaging optical system has a fixed pupil diameter, and as the focal length becomes larger, the relative aperture becomes smaller, resulting in a lower signal-to-noise ratio and weaker detection capability. Additionally, aberration correction is vitally important in the off-axis reflective zoom system with large relative aperture. An attempt to improve the performance of an off-axis reflective zoom imaging system with large relative aperture using freeform surface is reported. The F number is 4, and the zoom ratio is 3. The optical design with freeform surfaces shows marked improvements compared with the design with higher order aspheric surfaces.

偏振成像是一种新型光电探测方法.相比于传统的强度成像,偏振成像可以进一步获取目标的偏振特性,从而提高对比度,增加识别概率.偏振成像在生物医疗、工业检测、地球遥感、现代军事以及海洋和航空领域具有重要应用价值.文中对偏振成像系统的成像方式进行分类和比较,总结了偏振成像的实现方法.在此基础上,根据不同偏振成像系统的特点,针对不同的应用背景,对偏振成像系统的未来发展方向进行了展望,包括基于超表面的新型偏振成像系统以及新型偏振成像光谱系统等.