【作者】 张仲海；

【导师】 蒋秀珍；

【作者基本信息】 哈尔滨工业大学 ， 仪器科学与技术， 2009， 硕士

【摘要】 双光纤共球耦合结构适于在深入狭小的半封闭空间和易燃易爆环境下进行精密测量。基于双光纤共球耦合原理的内尺寸测量传感器,具有高分辨力,高精度的特点,可以精密测量用传统测量方法和技术难以进行的微深腔体及沟槽等结构。研究双光纤耦合过程中光能量场的分布规律,分析耦合效率的影响因素,将为双光纤耦合原理在提高内尺寸测量传感器的综合性能方面打下理论基础。针对现有光线模型的不足,本文首先依据电磁问题的解析方法研究并分析单光纤在柱坐标系下和单球体在球坐标系下矢量波与标量波及其关系;研究矢量波加法并获得柱矢量波的坐标变换关系;通过柱标量波的球标量波分解式得到光纤内标量驻波在耦合球内的球矢量波展开式。研究Debye级数与Mie系数之间的关系,进而获得球行波的反射和透射系数及球体远场分布。结合双光纤共球耦合结构的尺寸特点及相关电磁分析方法,本文推导出双光纤共球耦合结构的近似数学模型。在近似模型中,耦合球结构的场分布通过将耦合球划分为不同区域并分别求得散射系数的方法求得。光纤模式系数则是通过球模场的正交性及定域积分等获得。分析并给出数学模型中散射系数的数值算法。由双光纤共球耦合结构对称特点,采用有限时域差分法分析双光纤共球耦合结构在传光平面上的场分布。结合现有微球,微柱电磁散射的远场测量方案,与耦合球结构的空间特性,提出耦合球结构的远场光强分布测量方案。由测量方案中成像关系得到耦合球定位方法及远场光强分布测量的主要影响因素。最后通过实验,证明了双光纤共球耦合结构的近似数学模型的正确性。更多还原

【Abstract】 Double optical fiber ball coupling structure can be worked in a semi-enclosed space or a flammable and explosive enviromnet. Comparing with traditional methods and techniques, the inner dimension measuring sensor based on the princple of double optical fiber ball coupling canbe uesed in the micro-cavity and the deep trench to complete a high-resolution, high-precision measuring. By analyzing the impact of coupling efficiency factor and energy distribution of double optical fiber ball coupling field, which lay the foudation for the next research on the improving of comprehensive performance of the inner dimension measuring sensor.For the disadvantage of ray-tracing model, this paper firstly analyze the field in a single optical fiber and a single sphere, and get the relation between the vector wave and scarlar wave. In this paper, the theory of vecto addtion and the expansion of the cylinder wave is studied and applied in ball coupler. By researching on the Mie-Debye series, the reflection and transmission coefficients of spherical wave is computed. According the feature of the Double optical fiber ball coupling structure, the inner and outer field of ball coupler is given by dividing the ball coupler into different zones. With the outer and inner field of ball coupler, the far field can be directly acchieved. The optical fiber mode coeffecent can be obtained by the boundary condition (the surface of the ball coupler and the transerve surface of the optical fiber)and the Lorentz reciprocity .By the study of FDTD, this paper give a experiment for the whole structrure.With the result, the disadvantage of the FDTD is give and the model is approved basiclly.According the existing far field measuring system of microspherr and micro cylinder and the feature of the ball coupler, we propose a new measuring system for the ball coupler. By a real structure experiment, the model is supported and testified.更多还原