文档介绍：沈阳理工大学硕士学位论文

摘要

随着科技的发展,液压系统在工业生产中扮演的角色日益重要,液压油质量
的好坏直接影响到液压系统的稳定性,水作为液压油中主要污染物是油品检测的
重要内容之一。本文在研究了现有油中水检测方法的基础上,提出了一种基于光
声光谱技术检测油中水的方法,这种检测方法灵敏度高,特别适合对微量样品和
弱吸收样品的检测,并且这种检测方法具有不污染待测样品的优点。
本文首先阐述了光声信号的产生机理,分析了光声光谱检测的 RG 理论,将
光声光谱法与其它几种光谱检测方法进行比较,介绍了光声光谱检测的特点和应
用领域,并且将这种检测方法应用到油中水的检测当中。通过实验结果证明光声
光谱检测是一种灵敏度很高的光学检测方法。
然后在搭建硬件实验平台的过程中,设计制作了光声池,开发了机械斩波器,
搭建了前置放大电路,采用半导体激光器作为光源,应用滤光片滤除其它波长光
线,使用微音器采集水的光声信号,通过锁相放大器进行了除噪处理。在此基础
上,本文采用 ARM9 芯片开发了数据处理模块,在嵌入式芯片中采用 Windows CE
操作系统,通过对操作系统的裁剪和 AD 转换驱动程序的开发将光声池产生的光
声信号采集到数据处理模块中。
最后数据处理模块将采集到的光声信号进行除噪处理,通过对几种经典滤波
方法的理论分析和比较,本文选择了 Mallat 算法对水的光声信号进行除噪滤波。
Mallat 算法是一种正交小波的多分辨率变换,利用这种方法处理光声信号取得了
很好的滤波和除噪效果。

关键词:光声光谱;油中水;Mallat 算法;ARM9
沈阳理工大学硕士学位论文

Abstract

With the development of technology, the hydraulic system plays an increasingly
important role in industrial production, and the quality of the hydraulic oil affects the
stability of the hydraulic system immediately. The content of water, as the main
pollution in the hydraulic oil, is one of essential norms of oil detection. The thesis
study of current method to detect the water content in oil and proposes a method based
on the technology of photoacoustic spectrometry. This is a kind of optical detection
technology with high sensitivity, and it is particularly suitable for the detection of
micro samples and weak absorption samples. Besides, this detection method could not
contaminate the samples.
First of all, this thesis describes the generation mechanism of the photoacoustic
signals, analyzes the RG theory of photoacoustic spectrometry detection, compares the
photoacoustic spectrometry with some other methods of spectral detection, introduces
the features and the applicative field of the photoacoustic spectrometry detection, and
applies this detection method to detect the water content in oil. Through experiments, it
is proved that the photoacoustic spectrometry detection is a kind of optical detec