1 中国科学院上海光学精密机械研究所空间激光信息传输与探测技术重点实验室, 上海 201800
2 中国科学院大学材料与光电研究中心, 北京 100049
多芯光纤中有多个独立并行的空间信道,利用其实现空间分集,以解决基于传统单模光纤的分布式光纤声波传感系统所面临的信号衰落和信噪比受限问题。通过扇入扇出模块,在多芯光纤的其中四个纤芯中进行信号的独立传输和分集探测,并采用相干合并技术对多路信号进行有效合并。实验结果表明,外部扰动信号得到了很好的重构,信号衰落被抑制,系统的底噪较优化后单模光纤系统降低了5.2 dB。传感器表现出高水平的性能,带宽可达10 kHz,最低底噪达-85 dB。
光纤光学 多芯光纤 分布式声波传感 底噪
1 中国工程物理研究院 激光聚变研究中心，四川 绵阳 621999
2 东南大学 生物科学与医学工程学院，江苏 南京 210096
针对参考时钟源高电平脉冲宽度窄(小于2?ns)和本底噪声大的问题，通过使用一种时钟低抖动整形技术方案，使参考时钟经过锁相整形后高电平脉冲宽度大于3?ns、锁相相位时间抖动均方根(RMS)值小于5?ps。目前该方案已成功用于星光III激光装置的联机实验，情况良好，对其他类似需要精密时钟的装置具有极大的借鉴意义。
脉冲宽度 本底噪声 低抖动 时钟整形 信号完整性 pulse width noise floor low jitter clock reshaping signal and power integrity 太赫兹科学与电子信息学报
2018, 16(6): 1109
Author Affiliations
Abstract
Center for Molecular Imaging The Brown Foundation Institute of Molecular Medicine The University of Texas Health Science Center at Houston Houston, TX 77030, USA
Near-infrared fluorescence (NIRF) imaging involves the separation of weak fluorescence signals from backscattered excitation light. The measurement sensitivity of current NIRF imaging systems is limited by the excitation light leakage through rejection filters. In this contribution, the authors demonstrate that the excitation light leakage can be suppressed upon using appropriate filter combination and permutations. The excitation light leakage and measurement sensitivity were assessed and compared in this study by computing the transmission ratios of excitation to emission light collected and the signal-to-noise ratios in well-controlled phantom studies with different filter combinations and permutations. Using appropriate filter combinations and permutations, we observe as much as two orders of magnitude reduction in the transmission ratio and higher signal-to-noise ratio.
Molecular imaging fluorescence optical filter excitation light leakage noise floor Journal of Innovative Optical Health Sciences
2011, 4(3): 301
