共查询到20条相似文献,搜索用时 14 毫秒
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Fiber-optic acoustic sensors are being developed for the detection and location of partial discharges in oil-filled transformers. The partial discharges can be detected acoustically and located by the triangulation method with the sensors placed inside the transformer tank. In this application, the directionality of the sensor should be as flat as possible within at least ±40° from the sensor axis and for a frequency range up to 150 kHz. A calculation of the directionality of a fiber coil acoustic sensor was made using a plane wave approximation. The calculation showed that if the diameter of a fiber coil is less than 20 mm, its directionality is relatively flat within ±300 for frequencies lower than 150 kHz. The directionality of an optical fiber acoustic sensor for the frequency range of 50-300 kHz was measured experimentally in an oil tank. The effect of reflected waves was avoided by using a gating technique. The experimental results show somewhat different directionality patterns from the theoretical results but are internally consistent and with maxima and minima at frequencies close to those predicted. The discrepancy is believed to be due to a resonance effect which is not taken into account in the theoretical model. However, the sensor achieves the directionality performance required for the application 相似文献
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基于膜片的光纤布拉格光栅压力传感器的研究 总被引:2,自引:0,他引:2
理论分析了光纤布拉格光栅的压力传感特性,给出了光纤布拉格光栅的中心波长与压力的关系以及压力灵敏度系数的表达式,并将光纤布拉格光栅纵向粘贴在自行设计型号为ZXYC01的平面膜片上进行了压力实验.实验结果表明光纤布拉格光栅压力灵敏度系数46 pm/MPa左右,其测量精度为0.5%F.S,而理论的压力灵敏度系数为51 pm/MPa左右,实验值和理论值基本相符,它们分别是裸光纤布拉格光栅压力灵敏度系数的23和26倍.同时发现光纤布拉格光栅的中心波长与压力变化有着良好的线性关系和很高的相关系数并且迟滞现象较小. 相似文献
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针对机场、油库等特定区域的高识别率、低误报率入侵事件监控需求,提出了一种基于光纤传感与红外视频的目标识别方法。其中,光纤传感部分采用基于MCSVM的非对称双马赫-曾德尔干涉仪(ADMZI)分布式光纤振动传感器,将EMD(经验模式分解)、将峰度特征与MCSVM相结合以提高识别率;红外识别部分将灰度差值图像通过小波变换提高清晰度。两者经过模式对比算法,实现入侵事件判定。搭建系统做现场实验,结果表明:该方法能够识别四种常见的入侵事件(爬越围栏、敲击电缆、剪断围栏、摇动围栏),平均识别率在92.5%以上,误报率0.9%,相对传统单一传感器方案,该方法在漏报率和虚警率等系统性能上都有较大的改善,能够满足实际应用要求。 相似文献
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旅游安全事故具备突发性与不确定性等特点,传统检测方法不具备实时检测功能,无法及时检测到潜在风险,为此提出了基于光纤传感器实时采集信息的旅游安全检测方法,提升检测效果,降低风险威胁指数.通过光纤传感器构建CCD成像模型,实时采集图像信息;利用几何不变矩阵提取实时采集图像信息内的特征;将提取的特征作为支持向量机的输入,输出... 相似文献
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全光网络是通信网络发展的大趋势,光纤传感器因其所特有的特性具有电子传感器所无法比拟的优势。介绍了全光网络的结构和对全光网络可能采取的攻击方式,讨论了如何利用光纤传感器对针对全光网络的攻击进行检测。 相似文献
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A single-mode-few-mode-thin-core-single-mode (SFTS) structure based optical fiber sensor is fabricated and experimentally studied. The sensing principle relies on the inter-modal interference. Since the core diameter of few-mode fiber (FMF) is larger than that of single-mode fiber (SMF), the FMF helps to allow more light to enter the cladding of thin-core fiber (TCF), which helps TCF to excite cladding modes. The interference between core and cladding modes in TCF occurs at the joint of lead-out SMF and TCF. Experimental results demonstrate a refractive index (RI) sensitivity of ?103.34 nm/RIU and a temperature sensitivity of 0.05 nm/°C. The proposed sensor not only can measure temperature, but also can measure RI. In addition, the proposed sensor is simple for without complicated fabrication process. 相似文献
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基于SU-8的微透镜阵列的设计和制作 总被引:1,自引:1,他引:0
以SU-8作为结构材料,采用紫外光刻工艺,尤其以斜曝光工艺为主,加工出主光轴平行于衬底基片的微透镜阵列,单个微透镜的直径大约为500μm。初步确定出加工此透镜所需要的曝光剂量、前烘时间、后烘时间和显影时间,为加工其他尺寸的透镜提供参考。基于此方法加工的微透镜阵列能够对光束进行聚焦、反射、衍射、相位调制等控制,从而可最终实现光开关、衰减、扫描和成像等功能,为其他微型光学器件,如分光镜和反射镜等的系统集成提供极大的便利。同时,此微透镜阵列也会被集成在微流细胞仪中用来对流式细胞仪中样本流做荧光检测,极大地提高了检测的精度。 相似文献
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A. ZizzariV. Arima A. ZacheoG. Pascali P.A. SalvadoriE. Perrone D. MangiulloR. Rinaldi 《Microelectronic Engineering》2011,88(8):1664-1667
SU-8 is a very interesting material for the fabrication of lab-on-chip devices applied to organic synthesis because of its resistance to chemicals and solvents. Among the possible application fields of microreactor technology, radiochemistry is emerging because microfluidic apparatuses allow to perform radiosynthesis in a quicker, safer and more reliable way compared to traditional vessel-based approaches. Microreactors for synthesizing [18F]-labelled radiopharmaceuticals require the employment of materials that do not adsorb fluoride and are resistant to solvents and chemicals. Pyrex, glass and silicon adsorb fluoride ions, therefore they are not the best choice. SU-8 is stable towards chemicals and solvents but nothing is known about its behaviour with radioactive fluoride. Here we develop a simple fabrication procedure to make fully coated SU-8 microreactors and we demonstrate the potentiality of SU-8 microfluidic architectures to be used for radiosynthesis, giving a proof of their low tendency to trap radioactive fluoride if compared with traditional glass microchannels. 相似文献
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Fe-C合金膜光纤腐蚀传感器的制作及性能研究 总被引:1,自引:0,他引:1
为了在光纤纤芯上制备更符合要求的Fe-C合金膜,取代了氢氟酸(HF)腐蚀包层的方法,选用刀笔去除光纤的涂覆层和包层;分别使用物理气相沉积离子溅射金及Fe-C合金、物理气相沉积真空蒸镀Fe-C合金、化学镀铜4种方法使纤芯表面金属化.经过对比分析,选择在金膜和铜膜上继续利用电镀方法沉积上不同厚度的Fe-C合金膜,进而进行腐蚀传感实验.最后利用新的实验数据记录方法,并通过实验中不同厚度的Fe-C合金膜表现出的传感特点,提出了一个腐蚀定量监测方案.结果表明,通过离子溅射金使纤芯金属化是一个相对较好的方法,这为Fe-C合金膜光纤腐蚀传感器的进一步发展开启了新思路. 相似文献
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为了在光纤纤芯上制备更符合要求的Fe-C合金膜,取代了氢氟酸(HF)腐蚀包层的方法,选用刀笔去除光纤的涂覆层和包层;分别使用物理气相沉积离子溅射金及Fe-C合金、物理气相沉积真空蒸镀Fe-C合金、化学镀铜4种方法使纤芯表面金属化。经过对比分析,选择在金膜和铜膜上继续利用电镀方法沉积上不同厚度的Fe-C合金膜,进而进行腐蚀传感实验。最后利用新的实验数据记录方法,并通过实验中不同厚度的Fe-C合金膜表现出的传感特点,提出了一个腐蚀定量监测方案。结果表明,通过离子溅射金使纤芯金属化是一个相对较好的方法,这为Fe-C合金膜光纤腐蚀传感器的进一步发展开启了新思路。 相似文献
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采用基于Sagnac的保偏光子晶体光纤(polarization-maintaining photonic crystal fiber,PM-PCF)滤波器,将宽带光源精确匹配甲烷气体在近红外波段的几个吸收线谱.设计出一个简单合理的多反射气室,使得光源和甲烷气体之间能够充分相互作用,提高了系统的灵敏度.同时,在测量甲烷气体浓度时,加入乙炔气体作为干扰,通过实验验证了该方案能够有效减缓交叉气体的灵敏度. 相似文献
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Simulation and analysis for microstructure profile of optical lithography based on SU-8 thick resist
《Microelectronic Engineering》2007,84(5-8):1100-1103
Profile simulation of optical lithography is very useful for micro-fabrication of microstructure with high sidewall quality. In this paper the light wave propagation, exposure and development process were analyzed, and modeling for thick film lithography was developed to accurately and rapidly obtain simulated results. The effect of exposure dose on the profile quality after development were simulated and discussed, which show that these process parameters have a great impact on the profile quality of microstructure. With guidance of the simulation and analysis, the micro-gear and micro-piston of micro-motor fabricated by SU-8 thick resist were presented. 相似文献
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分布式温度传感(Distributed Temperature Sensing,DTS)技术是一种实时监测被测环境温度场的新型传感技术,较于传统的井温测量技术,具有无源工作、分布采集、布设简单等优势。煤层气井的开采对井下的剖面温度和产层流量都有着明确的计量需求。本文简要介绍DTS设备和产量解释的原理,结合DTS设备在国内某煤层气井的实际温度监测试验,验证了DTS在生产测井温度监测方面的可行性,并通过解释软件初步测算煤层气井产层流量。通过与传统的测试方式对比,目前分布式温度传感的测温精度和分辨率分别达到1℃和0.1℃,产层流量计算误差控制在大约3%的水平。 相似文献
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光纤表面等离子体共振(SPR)传感器是目前应用在环境介质检测和生物大分子检测等方面的新型、高精度传感器。首先,以表面等离子体共振传感理论为基础,对系统检测结果进行数据处理,得出采用均值估计的线性模型。在不同时刻与相同环境介质下,检测某一溶液的十组光谱数据并进行均值估计,从而得到有效的共振波长。其次,利用小波分析方法进行信号处理,校正了噪声产生的漂移,对光谱信号压缩处理,以提高检测精度。再通过Matlab进行模拟仿真优化传感系统性能。并对不同折射率溶液如蒸馏水、酒精等进行检测,得到了良好的光谱响应曲线,证明了在检测范围内折射率和共振波长之间具有良好的线性关系。 相似文献