基于Monte Carlo方法的激光粒子计数器信号仿真与粒径分辨率优化研究

发布时间：2018-06-03 15:13

本文选题：激光粒子计数器 + Monte　；参考：《南京理工大学》2017年硕士论文

【摘要】：光散射式尘埃粒子计数器是监测空气中悬浮颗粒的重要光学传感器,其粒径分辨率很大程度上影响着测量结果的准确性,其中最重要的影响因素是散射光收集系统的结构,本文从理论建模与实验验证的角度出发,研究不同散射光收集系统结构对粒径分辨率影响,为激光粒子计数器的优化提供了一种解决方案。本文以Monte Carlo随机模型为基础,针对粒径为0.3μm、0.4μm、0.5μm与0.6μm四种标准PSL粒子,建立单粒子Lorenz-Mie随机散射模型。同时将散射收集系统简化为光电探测器、光敏区与反射镜三个组成部分,对光电探测器光敏感面、光敏区进行有限元划分,推导计算空间光束反射坐标变换,理论计算散射光信号幅度分布曲线与光子落点位置时间积分结果,同时理论上探讨幅度呈对数正态分布的随机噪声模型的合理性,完成PartileCounter仿真软件编写;以信息熵为基础建立信号分布的离散度与区分度评价体系,通过仿真计算比较球形反射镜与椭球形反射镜对粒径分辨率的影响,同时寻找光电探测器最佳位置。实验上,对两台改进型粒子计数器与原有LM1612Ag型粒子计数器进行四种标准粒子的标定实验,获取实际信号幅度分布结果,验证理论模型的合理性,证明当探测器距球心4.5mm时粒径分辨率达92.6%,比原有结构粒径分辨率有较大提升,远超国标规定的70%。本文研究工作为散射光收集系统的优化提供了新的解决思路,为粒径分辨率的提升提供了理论依据。
[Abstract]:The light scattering dust particle counter is an important optical sensor for monitoring suspended particles in the air. The resolution of particle size greatly affects the accuracy of the measurement results. The most important factor is the structure of the scattering light collection system. In this paper, from the point of view of theoretical modeling and experimental verification, the influence of different light collection system structures on particle resolution is studied, which provides a solution for the optimization of laser particle counter. Based on the Monte Carlo stochastic model, a single particle Lorenz-Mie random scattering model is established for four standard PSL particles of 0. 3 渭 m ~ 0. 4 渭 m ~ 0. 5 渭 m and 0. 6 渭 m. At the same time, the scattering collection system is simplified into three parts: photodetector, Guang Min region and reflector. The photo-sensitive surface and Guang Min region of photodetector are divided by finite element method, and the spatial beam reflection coordinate transformation is deduced and calculated. At the same time, the rationality of random noise model with logarithmic normal distribution of amplitude is discussed theoretically, and the PartileCounter simulation software is written. Based on information entropy, an evaluation system of dispersion and differentiation of signal distribution is established. The influence of spherical mirror and ellipsoidal mirror on particle size resolution is compared by simulation, and the optimum position of photodetector is found at the same time. In the experiment, two modified particle counters and the original LM1612Ag particle counter were calibrated by four kinds of standard particles, the results of the actual signal amplitude distribution were obtained, and the rationality of the theoretical model was verified. It is proved that the particle size resolution of the detector is 92.6when the detector is away from the spherical center 4.5mm, which is much higher than that of the original structure, which far exceeds the 70th specified in the national standard. The research work in this paper provides a new solution for the optimization of scattering light collection system, and provides a theoretical basis for improving the resolution of particle size.
【学位授予单位】：南京理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TH744.5

【参考文献】