【作者】 胡轶；

【导师】 郑筱祥； 叶树明；

【作者基本信息】 浙江大学 ， 生物医学工程， 2014， 博士

【摘要】 海洋原位传感器是人类感知海洋的触角,是海底观测网的重要组成部分,对人类了解海洋认识海洋具有重要意义。原位光学传感器具有检测精度高、探头不易污染、稳定性高的优点而成为海洋原位监测仪器的主流。在恶劣的海洋原位环境下,海洋原位传感器的性能不仅在于传感器本体的测量灵敏度,更在于系统抗干扰能力。论文研究围绕传感器测量灵敏度与系统抗干扰能力这一对相辅相成而又互相制约的矛盾展开研究,寻求最优平衡。论文提出了微弱光学信号测量模型,在此基础上对海洋原位叶绿素a传感器、原位浊度传感器和原位CDOM(Colored Dissolved Organic Matter, CDOM,有色溶解有机物)传感器展开研究。论文的主要研究内容和创新点包括：1.建立了原位光学传感器的微弱光学信号测量模型,从电子测量的角度将原位叶绿素a检测、原位浊度检测和原位CDOM检测统一,研究了调制序列、干扰和噪声之间的关系；解决了微弱光学信号测量的光路、结构、精密检测等传感器设计关键问题,研制了基于单频调制方案的微弱光学信号系列传感器,实现了阳光背景干扰下微弱光学信号的高精度检测。实验结果表明,基于单频调制系统的原位叶绿素a传感器测量灵敏度达到0.0081μg/L,线性度R2=0.9985,优于Seapoint、Wetlabs公司同类产品。2.提出了带宽约束条件下基于伪随机序列的微弱光学信号测量方法及最小频谱幅值损失指标eN,优化了在有限带宽下m序列长度与测量精度的关系,提高了测量系统对窄带干扰的抑制能力。实验结果表明,伪随机序列在码长15bits和31bits时有最小系统测量噪声,码长31bits时比传统单频调制抗干扰能力提高了2.3倍。3.应用有限带宽下伪随机序列调制测量的优化结果,设计了原位叶绿素a传感器、原位浊度传感器、原位CDOM传感器,采用码长为31bits的m序列调制,其灵敏度分别为:0.0103μg/L(叶绿素a标定)、0.0078FTU(福尔马肼标定)、0.137μg/L(硫酸奎宁标定)。4.论文研制的原位叶绿素a传感器和原位浊度传感器应用于南海浮标长期观测实验,原位浊度传感器完成了“蛟龙号”深潜器下潜实验,仪器工作正常,初步验证了传感器具有较高的测量精度、抗干扰能力和可靠性。论文研究解决了在复杂强干扰环境下徽弱信号的精确定量测量问题,提出了一种新型的微弱信号检测抗干扰方法,实现了在不增加硬件成本的基础上传感器抗干扰能力的提高。该研究具有重要的科学意义和实际应用价值。更多还原

【Abstract】 Marine in-situ sensor, which is an important part of undersea observatory network, has great significance for human to observe and understand the ocean. As the optical sensors are not easily contaminated and have the advantage of high precision and stability, in-situ optical sensors have become the mainstream of instrumentations for marine survey. In natural harsh environment, the performance of the sensor is not only determined by the sensitivity, but also by the anti-interference ability of the system. This thesis discussed on how to seek the optimal balance between the sensitivity and anti-interference ability of the system, the two contradictions which complement each other and restrict each other. This thesis had put forward an ultra-weak optical signal detecting model and developed in-situ chlorophyll-a sensor, in-situ turbidity sensor and in-situ CDOM (Colored Dissolved Organic Matter, CDOM) sensor.The followings are innovations and main parts of the thesis:1. Ultra-weak optical signal detecting model of in-situ optical sensor was set up; this model unified in-situ chlorophyll-a detection、in-situ turbidity detection and in-situ CDOM detection from the perspective of electronic measurement. Based on this model, the thesis studied the correlation among noise、interference and modulation sequence and designed the light detecting light path, mechanical structure and high precision electrical circuits of the optical sensor. In situ optical sensor with single frequency modulation method was developed, and realized the ultra-weak light signal detecting with sunlight interference existed. Experiments showed that the in-situ chlorophyll-a sensor with single frequency modulation method had a sensitivity of0.0081μg/L, with R-square0.9985. This result was better than the similar products from Seapoints Inc. and Wetlabs Inc.2. Ultra-weak optical signal detecting method based on pseudo-random sequence with constrains of band-pass signal pass was proposed to improve the anti-interference ability of the system. Minimum loss power spectrum index eN was developed to optimize the length of m sequence to get high precision detecting with constrains of band-pass signal pass. Experiments showed that the m sequence modulation with length of15bits and31bits had the minimum system noise, and the anti-interference of31bits modulation system was2.3times better than single frequency modulation system.3. The m sequence with length of31bits and chip time1/4096s is the most suitable modulation sequence method in this study. Based on this modulation method, the in-situ chlorophyll-a sensor, in-situ turbidity sensor and in-situ CDOM sensor were developed. The sensitivity of these sensors are0.0103μg/L(chlorophyll-a calibrated),0.0078FTU(chlorophyll-a calibrated、0.137μg/L(Quinine calibrated)。4. In-situ chlorophyll-a sensor and in-situ turbidity sensor developed in this work had been applied in long-term buoy observation experiments in the Southern China Sea successfully. In situ turbidity sensor has accomplished the’JiaoLong’deep-sea diving experiment with good performance. These indicate that sensors developed in this work have high precision, high anti-interference ability and reliability.In conclusion, this thesis solved the ultra-weak light detecting under sunlight and other electrical interference, and proposed a novel ultra-weak light detecting method. This method improved the anti-interference ability of the sensor without increasing the complexity of the system’s hardware. This study has important scientific significance and application value.更多还原