基于光电倍增管的数据采集系统设计

发布时间：2018-05-24 13:54

本文选题：微弱信号检测 + 光电倍增管　；参考：《长春理工大学》2017年硕士论文

【摘要】：随着科技的不断进步,微弱信号检测被提出了更高的要求。在对极微弱光信号进行光谱采集时,为了能探测到更微弱的光信号,有效提取被噪声湮没的待测信号,本课题基于光电倍增管设计了微弱光电信号的采集系统,它能够探测光功率在nW级别的微弱光信号,并有效地放大微弱待测信号,同时滤除不相关的噪声信号,提高采集系统的信噪比。课题首先将光源进行调制,然后采用Omni-λ150系列光栅型光谱仪进行分光,其光谱扫描范围为185nm~远红外,准确度为0.25nm(1200g/mm光栅),最小步距达0.01nm,选择光电倍增管作为光电探测器,相比其他光电探测器,它具有高增益、高频率响应和大信号接收区域等优点。在深入研究相关参数和特性后,课题搭建了光电倍增管的低噪声高压偏置电路和光电信号输出电路,针对光电倍增管输出的微弱光电信号,构建匹配的调理电路来放大微弱信号、滤除噪声信号。调理后的模拟电压信号通过模数转换芯片转换为数字量,送入可编程门阵列(FPGA)中进行信号相关解调、数字低通滤波等数字化处理。微处理器接收FPGA处理后的数据并打包发送至上位机显示处理平台,最后显示处理平台将采集的数据绘制成光谱曲线。实验结果表明采集系统能够探测到波长在360~840nm、光功率在0.1nW~0.2mW范围内的微弱光信号,光谱响应的峰值在420nm波长处。
[Abstract]:With the continuous progress of science and technology, weak signal detection has been put forward higher requirements. In order to detect the weaker light signal and extract the signal to be obliterated by noise effectively, a collection system of weak photomultiplier signal is designed based on photomultiplier tube. It can detect the weak optical signal at the level of nW, amplify the weak signal effectively, filter the irrelevant noise signal, and improve the signal-to-noise ratio (SNR) of the acquisition system. First, the light source is modulated, and then the Omni- 位 150 series grating spectrometer is used to separate the light. The spectral scanning range is from 185nmto far infrared, the accuracy is 0.25nm(1200g/mm grating, the minimum step distance is 0.01nm. the photomultiplier tube is chosen as the photodetector. Compared with other photodetectors, it has the advantages of high gain, high frequency response and large signal receiving area. After deeply studying the related parameters and characteristics, the low noise high-voltage bias circuit and the output circuit of the photomultiplier tube are built, aiming at the weak photomultiplier output signal. A matching conditioning circuit is constructed to amplify the weak signal and filter the noise signal. The analog voltage signal is converted into digital signal by A / D conversion chip, and then it is sent to FPGA for signal correlation demodulation, digital low-pass filtering and other digital processing. The microprocessor receives the data processed by FPGA and sends them to the host computer display and processing platform. Finally, the display processing platform draws the collected data into spectral curve. The experimental results show that the system can detect weak optical signals with wavelength of 360 nm and 840 nm and optical power in the range of 0.1nW~0.2mW. The peak value of spectral response is at the wavelength of 420nm.
【学位授予单位】：长春理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP274.2

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