针对远场激光光斑分布不均匀、形状不规则的特性，提出一种基于改进的Zernike矩的远场激光高精度中心测量方法。在传统Zernike矩亚像素边缘检测基础上，使用新型的logistic边缘检测模型和阶跃阈值自适应提取方法，在减少人工对阶跃阈值误判的同时，提高对实际边缘的识别精度，最后使用最小二乘法椭圆拟合得到高精度激光光斑中心。该方法在远场激光中心检测中，单帧误差在0.5 pixel左右，连续多帧中心偏差波动在1 pixel以内，拥有较高的精度和可靠的稳定性。

为了简化实时相干自由空间光（FSO）/无线传输系统结构并降低成本，文章基于带通Delta-Sigma调制（DSM）技术，实现了一个低成本的FSO系统。带宽为400 MHz、速率为1.6 Gbit/s的256进制正交振幅调制（256-QAM）信号经DSM后，生成10 Gbit/s偏振复用-正交相移键控（PDM-QPSK）信号，在50 m的FSO链路中实现实时传输，且该系统的灵敏度达到-46.2 dBm。从而证明，相干检测和带通DSM的结合将是未来光无线场景的一种有前途的技术。

Overview: In many scenes in real life, collecting high-quality images is one of the key factors to achieve high accuracy in object detection, image segmentation, automatic driving, medical surgery, and other works. However, images and videos collected by electronic devices are very vulnerable to various environmental factors, such as poor lighting, resulting in low image brightness, color distortion, more noise, effective details, and texture information loss, which brings many difficulties to subsequent tasks and works. The enhancement of low-illumination images generally restores image clarity by increasing brightness, removing noise, and restoring image color. In recent years, the depth neural network has had a strong nonlinear fitting ability, which has achieved good results in low illumination enhancement, image deblurring, and other fields. However, the existing low illumination image enhancement algorithms will lead to color imbalance when improving image brightness and contrast, and easily ignore the impact of some noises. Based on the above questions, this paper proposes an image enhancement method with parallel mixed attention step-by-step fusion. With the aid of the limited correlation between local features extracted by weighting different multi-scale branches, the local image details under multiple receptive fields can complement each other, and use parallel mixed attention to focus on color information and lighting features at the same time, which effectively improves the detail representation of the network and reduces noises. Finally, shallow feature information is fused in multiple stages. In order to alleviate the model confusion caused by the weakening of color information expression and single-stage feature superposition caused by the increase of network depth. The ablation experiment, module multi-stage experiment, and multiple evaluation indexes are compared with the existing advanced methods on four commonly used datasets, which fully proves that the method proposed in this paper is superior to the comparison methods on multiple evaluation parameters, and can effectively improve the overall brightness of the image, adjust the image color imbalance and remove noises. Combining the follow-up research task of the subject and analyzing the shortcomings of the network, a way to simplify the model and improve the operation speed will be the key direction of the follow-up research task.

为了维持发射机的稳定，以保证输出信号的质量，文章提出了一种新型的基于导频的自动偏压控制方案，可用于高阶调制格式。文章所提方案要求向调制器加载正交导频，并将经过移频的本振光与调制器输出的信号光相拍以实现相干探测。通过相关运算并监测相关系数值的方式，实现对偏置电压的控制。此方案将相干探测和相关检测技术结合，可有效提高系统的灵敏度，并通过仿真对此方案在高阶调制系统中的可行性以及对灵敏度的提升进行了充分验证。