为进一步提升空中作战条件下目标检测的性能, 本文通过优化 YOLO v3, 提出了一种基于空中红外目标的检测算法 EN-YOLO v3。该算法使用轻量的 EfficientNet骨干网络作为 YOLO v3的主干特征提取网络, 使模型参数大幅减少, 降低模型的训练时间; 同时选用 CIoU作为模型的损失函数, 优化模型损失计算方法, 提升模型的检测精度。结果表明, 优化后的 EN-YOLO v3目标检测算法与原 YOLO v3相比模型尺寸减少了 50.03%, 精准度提升了 1.17%, 能够有效提升红外场景下空中目标的检测效果。
红外场景 空中目标检测 模型优化 infrared scene, aerial target detection, YOLO v3, YOLO v3
光子学报
2021, 50(11): 1128002
本文设计了一种基于长程等离子波导的表面增强拉曼光流体芯片, 利用介质波导激发等离子波导的耦合结构减小传输损耗, 增加传输距离, 以实现拉曼信号的长程探测。在632.8 nm的激发光入射下, 以金(Au)作为等离子波导芯层材料, PTFE做为介质光波导芯层材料, 经仿真分析发现: 介质光波导宽度为4 μm、厚度为0.2 μm, 等离子体波导宽度为4.5 μm、厚度为13 nm, 两波导间距D为3.1 μm时, 耦合效果最好, 场强大小约1.8024×108, 传输距离约0.3 mm, 是单独使用等离子波导传输距离的两倍。该研究为实现表面增强拉曼微流体芯片长程探测提供了理论依据。
等离子波导表面增强拉曼散射 长程探测 plasma waveguide surface-enhanced Raman scattering long-range detecting
本文设计了一种基于长程等离子波导的表面增强拉曼光流体芯片, 利用介质波导激发等离子波导的耦合结构减小传输损耗, 增加传输距离, 以实现拉曼信号的长程探测。在632.8 nm的激发光入射下, 以金(Au)作为等离子波导芯层材料, PTFE做为介质光波导芯层材料, 经仿真分析发现: 介质光波导宽度为4 μm、厚度为0.2 μm, 等离子体波导宽度为4.5 μm、厚度为13 nm, 两波导间距D为3.1 μm时, 耦合效果最好, 场强大小约1.8024×108, 传输距离约0.3 mm, 是单独使用等离子波导传输距离的两倍。该研究为实现表面增强拉曼微流体芯片长程探测提供了理论依据。
等离子体波导 表面增强拉曼散射 远程探测 plasma waveguide surface-enhanced Raman scattering long-range detecting
Author Affiliations
Abstract
1 School of Electrical and Information Engineering, Tianjin University, Tianjin 300072, China
2 School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin 300072, China
3 Photonics Research Center, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China
In this study, a high-sensitivity, high-spatial-resolution distributed strain-sensing approach based on a poly(methyl methacrylate) chirped fiber Bragg grating (CFBG) is proposed and experimentally demonstrated. Linearly chirped FBGs in a polymer optical fiber provide an alternative to the silica fiber owing to the lower Young’s modulus, which can yield a higher stress sensitivity under the same external force. According to the spatial wavelength-encoded characteristic of the CFBG, a fully distributed strain measurement can be achieved by optical frequency-domain reflectometry. Through time-/space-resolved short-time Fourier transform, the applied force can be located by the beat frequency originated from the space-induced time delay and measured by the differential frequency offset originated from the strain-induced dispersion time delay. In a proof-of-concept experiment, a high spatial resolution of 1 mm over a gauge length of 40 mm and a strain resolution of 0.491 Hz/με were achieved.
Photonics Research
2020, 8(7): 07001134
