【作者】 杨影；

【导师】 王莉田； 郑龙江；

【作者基本信息】 燕山大学 ， 测试计量技术及仪器， 2002， 硕士

【摘要】 光纤传感技术是海洋测量中应用广泛的重要技术之一。海藻是主要的海洋浮游植物，叶绿素a是海藻中的主要色素。因此，叶绿素a是水生态系统的一个重要参数，其含量是反映海水中浮游植物生物量或现存量的一项重要观测项目，也是计算初级生产力的基础。本系统在利用原有的浓度检测技术前提下，应用光纤作为传输传感元件并结合荧光技术，可以实现海藻浓度高精度的在线测量。本文的主要研究内容包括： (1)论述荧光测量法的基本原理及特点，对海藻叶绿素a的荧光特性进行分析，为激发光源、滤光片、光探测器的合理选择及使用奠定理论基础。 (2)设计荧光光纤测量系统的总体方案。根据光纤探头的结构、特点，建立荧光信号测量及传输的数学模型，为系统标定提供理论依据。 (3)采用He-Ne激光器作为激发光源，低损耗石英光纤束作为光信号传输通道，高灵敏度、低噪声光电倍增管作为荧光信号探测器，以及以光子计数器为核心的微弱信号检测电路，实现微弱荧光信号的激发、收集、传输、探测和处理。 (4)为了消除激发光源波动对测量结果影响，采用双光路双通道测量方式。为了有效分离叶绿素a所产生的荧光和激发光的散射光，采用高阻塞系数的干涉滤光片作为光谱滤光。 (5)对设计的测量系统设进行实验室定性分析研究，并得出实验结果，包括：叶绿素a的吸收和激发荧光的光谱特性谱线，荧光强度变化与海藻浓度变化之间的线性关系曲线，实验证明用荧光光纤法测量海藻浓度的可行性。更多还原

【Abstract】 Optical-fiber sensor is one of important technique widely used in the field of ocean measuring. Algae is the main ocean phytoplankton and chlorophyll-a is the main pigment of algae. Chlorophyll-a is one of the important parameters of water ecological system. Its content also is an important observation item which reflects phytoplankton’s biomass or stock on hand in the sea, and also the basis of calculating the primary productive forces. Basing on old consistency measuring skill, the system applies optical-fiber as transmitting device with fluorescent technique to realize high efficiency on-line measuring of alga concentration. The main contributions of this dissertation are as follows:The basic principle and characteristic of fluorescence measurement method are discussed. The fluorescence specific properties of alga chlorophyll-a in the sea are analyzed. Therefore theoretical basis is established for the reasonable selection of excitation light source , optical fiber and optical detector.The total scheme of fluorescent optical-fiber measuring system is designed. According to the structure and characteristic of optical-fiber probe, the mathematical model of the fluorescent measurement and transfer is established in order to provide theoretical foundation of system calibration.The system adopts weak signal measuring circuit with He-Ne laser as light house, low-loss silicon optical-fiber bundle as transmission channel of light signal, high sensitivity and low-noise PMT as fluorescent signal detector and photo counter as main detecting device to realize the excitation, collection, transmission, detection and processing of weak fluorescence signal.To eliminate the signal variation due to undulation of excited light source, the detecting method of double light routes and double channels at the same time are used. In order to effectively separate the fluorescence produced by algae chlorophyll-a and the scatting light from the excitation light, the interference filter with high block coefficient and narrow band is used as spectral filter.Qualitative analysis and research of the measuring system are processed in the lab to educe the results of experiments, including the absorbing and excited fluorescence spectra character of chlorophyll-a experiments. The linear curve between the variation of fluorescence density and variation of algae concentration is educed and validates the feasibility of the system.更多还原