近红外无创生化分析中高效光谱聚光系统研究

发布时间：2018-02-22 20:16

本文关键词： 蒙特卡罗模拟光纤椭球反射镜复合抛物面聚光器无创生化分析　出处：《中国科学院研究生院（长春光学精密机械与物理研究所）》2012年硕士论文　论文类型：学位论文

【摘要】：近红外光谱技术是血液无创生化分析能够获得应用的最具潜力的方法之一。但是,由于人体皮肤组织中的水对光的吸收非常强,并且血液中各种化学成分的含量较低,致使由它们引起的吸收光谱信号很微弱,给无创生化分析带来了困难。为了解决此问题,本论文通过增大光学系统集光效率的方法来增加近红外光谱分析系统的光通量,从而有助于提高光谱仪器的信噪比。论文首先介绍了近红外无创生化分析的研究现状,分析了当前存在的技术难点,包括光谱信号微弱、背景干扰及血流容积的周期性变化。针对第一个问题,拟采用设计高效聚焦光学系统的方法作为解决途径,提出对分别由光纤、椭球反射镜、复合抛物面聚光器构成的几种光学系统的聚焦效果进行研究。阐述了蒙特卡罗模拟方法原理,结合三层皮肤组织模型,研究了光在皮肤组织中的传播规律。在波长范围为1000nm-2350nm内,模拟计算了光子传播的路径长度、穿透深度、散射次数以及漫反射光能量,并讨论了入射-出射距离对出射光子能量的影响。根据以上蒙特卡罗模拟结果对光纤探头的结构进行了设计,并利用光学软件仿真计算了光纤收集到的漫反射光能量及照度分布。根据椭球反射镜的聚光特点,在几何光学理论的基础上计算了焦面上的物体经椭球镜反射后像点坐标方程,并基于此方法优化了椭球反射镜最佳聚光效果时的结构参数。采用光线追迹方法,分析了椭球反射镜聚焦光能特征,与无光学收集系统相比,椭球反射镜对人体漫反射光的利用率提高了5.4倍。分析了复合抛物面聚光器(CPC)反射光线随结构参数变化特点,优化设计了CPC-凹面镜系统结构参数。首次提出了一种双复合抛物面聚光系统,通过比较标准型和截短型CPC聚光性能变化,优化出集光效果最佳时的结构参数,并分别模拟研究了这两种光学系统对人体漫反射光的聚焦情况。与无光学收集系统相比,截短型CPC-凹面镜系统对人体漫反射光的利用率提高了15.1倍,截短型双复合抛物面聚光系统对人体漫反射光的利用率提高了32.6倍。本文研究的几种聚光系统均能有效地将漫反射光会聚至探测器上,有助于提高无创生化分析系统的信噪比及整体分析精度。
[Abstract]:Near-infrared spectroscopy (NIR) is one of the most promising methods for non-invasive biochemical analysis of blood. However, because of the strong absorption of light by water in human skin, and the low content of various chemical components in blood, The absorption spectrum signal caused by them is very weak, which brings difficulties to non-invasive biochemical analysis. In order to solve this problem, this paper increases the luminous flux of the near infrared spectrum analysis system by increasing the optical system's light collection efficiency. It is helpful to improve the signal-to-noise ratio of the spectrometer. This paper first introduces the research status of NIR noninvasive biochemical analysis, and analyzes the existing technical difficulties, including weak spectral signals, background interference and periodic changes of blood flow volume. The focusing effect of several optical systems composed of optical fiber ellipsoidal mirror and compound parabola concentrator is studied by using the method of designing high efficiency focusing optical system. In this paper, the principle of Monte Carlo simulation is described, and the propagation of light in skin tissue is studied in combination with a three-layer skin tissue model. In the wavelength range of 1000nm-2350nm, the path length and penetration depth of photon propagation are simulated and calculated. The scattering times and diffuse reflected light energy are also discussed. The influence of incident-exit distance on the emission photon energy is discussed. Based on the above Monte Carlo simulation results, the structure of optical fiber probe is designed. The energy and illuminance distribution of diffuse reflected light collected by optical fiber are simulated by optical software. According to the characteristics of ellipsoidal reflector, the image point coordinate equation of the object on the focal plane reflected by the ellipsoid mirror is calculated on the basis of geometric optics theory. Based on this method, the structure parameters of the ellipsoidal mirror are optimized. The focused light energy characteristics of the ellipsoidal mirror are analyzed by using the ray tracing method, which is compared with the non-optical collecting system. The utilization ratio of ellipsoidal mirror to diffuse reflected light is 5.4 times higher. In this paper, the characteristics of the reflected light of the compound paraboloid concentrator (CPC) are analyzed, and the structural parameters of the CPC- concave mirror system are optimized. A dual compound parabolic condenser system is proposed for the first time. By comparing the change of condensing performance between standard and truncated CPC, the structure parameters of the best light gathering effect are optimized, and the focusing conditions of the two optical systems on diffuse reflected light of human body are simulated and studied respectively. Compared with the non-optical collection system, the structure parameters of the two optical systems are simulated. The utilization ratio of the truncated CPC- concave mirror system for diffuse reflected light is increased by 15.1 times, and that of the truncated double-compound parabolic condenser system is increased by 32.6 times. In this paper, several condensed light systems can effectively converge diffuse reflected light onto the detector, which is helpful to improve the signal to noise ratio and the overall analytical accuracy of the non-invasive biochemical analysis system.
【学位授予单位】：中国科学院研究生院（长春光学精密机械与物理研究所）
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：R318.6;O433

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