TDLAS氧气检测系统设计及背景噪声在线消除  

Oxygen concentration detection system based on TDLAS and online elimination of background noise

作　　者：庞涛[1,2] 夏滑[1] 吴边[1] 张志荣[1] 王煜[1] 崔小娟[1] 董凤忠[1,2] 

机构地区：[1]中国科学院安徽光学精密机械研究所、安徽省光子器件与材料重点实验室,安徽合肥230031 [2]中国科学技术大学环境科学与光电技术学院,安徽合肥230000

出　　处：《光电子．激光》2015年第3期575-580,共6页Journal of Optoelectronics·Laser

基　　金：国家自然科学基金(11204320);国家“863”计划(2007AA06Z420)资助项目

摘　　要：将可调谐半导体激光吸收光谱(TDLAS)技术用于氧气(O2)浓度在线检测。以垂直腔表面发射半导体激光器(VCSEL)为系统光源,采用对射式结构,测量光程为60cm,选用760nm附近O2吸收谱线,实现O2浓度实时测量。连续72h测量表明,系统在短时间内具有较好的测量精度,长时间(大于4h)测量结果存在缓慢漂移。在对一次谐波(1F)信号均值和二次谐波(2F)信号峰值变化趋势分析的基础上,讨论了背景噪声随测量环境变化引起的测量误差;并在背景噪声幅频特性不变的前提下,利用最大互相关算法实时扣除背景噪声。5%浓度O260h测试发现,扣除背景噪声后,系统的最大相对测量误差由3.20%减小为1.82%,测量精度提高近1倍。Oxygen concentration detection plays an important role in industrial process control.In this paper,tunable diode laser absorption spectroscopy（TDLAS）is used for online monitoring of oxygen concentration.The experimental system employs vertical cavity surface emitting lasers（VCSEL）with output wavelength of 760 nm as light source and adopts the radio-type structure with optical path of 60 cm.Continuous measurement for 72 hours shows that the system has a high accuracy in short time,but slow drift comes out when the time is longer than 4hours.Based on the analysis of first harmonic signal and second harmonic signal,this paper argues that the changes of background noise causes measurement error,and the composition and characteristics of background noises of the system are carried out and discussed too.After analyzing the system signal from the perspective of frequency domain,we propose that under the premise of the amplitude-frequency characteristic of the system′s background noise keeping stable,cross-correlation algorithm could be applied to deduce the background noise in real-time.The test of 5% oxygen for 60 hours points out that after data processing,the maximum relative error is reduced from 3.2%to 1.82%.This indicates that the proposed method could effectively improve the system′s performance.

关 键 词：可调谐半导体吸收光谱(TDLAS) 垂直腔表面发射半导体激光器(VCSEL) 背景噪声 互相关 

分 类 号：O433.4[机械工程—光学工程]