A simple quasi-distributed fiber sensing interrogation system based on random speckles is proposed for weak fiber Bragg gratings (WFBGs) in this work. Without using tunable lasers or spectrometers, a piece of multimode fiber is applied to interrogate the WFBGs relying on the wavelength sensitivity of speckles. Instead of the CCD sensor, an InGaAs quadrant detector serves as the receiver to capture the fast-changing speckle patterns. A supervised deep learning algorithm of the multilayer perceptron architecture is implemented to process speckle data and to interrogate temperature changes or dynamic strains. The proposed demodulation system is experimentally demonstrated for WFBGs with 0.1% reflectivity. The experimental results demonstrate that the new system is capable of measuring temperature change with an accuracy of 1°C and achieving dynamic frequency of 100 Hz. This speckle-based interrogation system paves a new way for distributed WFBGs sensing with a simple design.

为研究系统级射频设备高功率微波前门效应，采用注入法对某4G基站的滤波器、环形器、低噪放及功放构成的射频前端进行实验研究。结果表明，高功率微波脉冲上升沿和下降沿被射频前端滤波器强烈反射，脉冲平顶段反射很小。反射波形在上升沿及下降沿呈尖峰、在脉冲中部呈平底，显示高功率微波陡峭的上升沿和下降沿包含的丰富的滤波器带外频率成分被反射，导致通过滤波器的脉冲头尾被削弱。经滤波器后，高功率微波脉冲可由环行器进入上行通道低噪放，进而被反射，环行进入下行通道功率放大器，被再次反射，再环行从注入口输出。实验中监测到了经两次反射环行的高功率微波脉冲。说明在高功率脉冲条件下，原本由环形器隔离的下行通道功率放大器同样会承受上行通道进入的高功率微波脉冲损伤的风险。

为克服非相干光源照明条件下基于全息光学元件的视网膜投影显示系统存在的色散、出瞳小、无法获得单眼调焦深度信息等局限，提出了一种基于双全息光学元件的3D视网膜投影显示器。用全息光学元件取代玻璃透镜，用发光二极管取代激光。用反射型体全息光栅和反射型体全息透镜构成的光学结构对系统的色散进行补偿，获得了清晰的图像，系统分辨率达到11.6 lp/mm。结合双全息光学元件结构，利用时分复用技术和角度复用技术实现了具有密集视点的3D视网膜投影显示。该结构可有效扩展系统的出瞳，解决视网膜投影显示系统出瞳小的问题。同时在0.45~2.0 m的深度范围内，实现具有单眼调焦深度信息的真3D显示，显示范围覆盖人眼的辐辏调焦响应敏感范围，可有效缓解辐辏调焦矛盾引起的眩晕和视觉疲劳问题。该系统结构紧凑、价格便宜且避免了散斑噪音和安全隐患，具有良好的应用前景。