光学学报, 2015, 35 (4): 0430001, 网络出版: 2015-04-03
基于可调谐半导体激光吸收光谱的CO和CH4实时检测系统设计
Design of Real-Time Measurement of Atmospheric CO and CH4 Based on Tunable Diode Laser Spectroscopy System
光谱学 可调谐半导体激光吸收光谱 直接吸收 实时检测 spectroscopy tunable diode laser absorption spectroscopy direct absorption real-time measurement
摘要
可调谐半导体激光吸收光谱(TDLAS)具有高灵敏度和高分辨率等特点,被广泛应用在痕量气体的快速检测中。研制了基于TDLAS 的开放式长光程CO 和CH4实时检测系统,采用直接吸收的方法,避免了波长调制技术中必需的浓度标定,结构简单。利用STM32进行数据采集处理,获取气体浓度值和光强变化值,通过串口屏实现浓度和光强值的在线显示以及浓度和光强随时间变化的曲线显示,并将浓度数据存储在SD 卡中,取代上位机操作,实现检测系统小型化。利用中心波长在2333 nm 附近的激光器结合直接吸收的方法,在往返750 m 的长光程上,对合肥市科学岛的大气CO 和CH4 进行同时检测实验。检测结果表明,大气中CO 浓度值整体低于CH4 值。对该系统进行长时间的测试,验证系统稳定性,CO 系统检测限为0.205 mg/m3,CH4为0.181 mg/m3。
Abstract
Tunable diode laser absorption spectroscopy (TDLAS) has a good prospect of application in rapid measurement of trace gases, due to its high resolution and high sensitivity. A real-time measurement system for atmospheric CO and CH4 based on open- path TDLAS is developed, which has a simple structure with direct absorption techniques, avoiding concentration calibration in wavelength modulation techniques. In the system, the data acquisition and processing is performed using a micro controller unit (MCU) of STM32, then the data is sent to DWIN graphical utilized software (DGUS), showing gas concentration and light intensity online, and the curves of gas concentration and light intensity versus time. The concentration and light intensity data is saved in the SD card. This system can replace the upper computer operation to achieve miniaturization. The system combining direct absorption method and a 2333 nm band laser is presented, and is utilized to monitor carbon monoxide and methane at Kexue Island of Hefei with 750 m optical path. The measurement result shows that the atmospheric CO concentration is lower than the CH4 concentration. The system has been tested for a long time to verify its stability, and its detection limit is 0.205 mg/m3 for CO and 0.181 mg/m3 for CH4.
李明星, 刘建国, 阚瑞峰, 姚路, 袁松, 戴云海, 魏敏, 许振宇, 阮俊. 基于可调谐半导体激光吸收光谱的CO和CH4实时检测系统设计[J]. 光学学报, 2015, 35(4): 0430001. Li Mingxing, Liu Jianguo, Kan Ruifeng, Yao Lu, Yuan Song, Dai Yunhai, Wei Min, Xu Zhenyu, Ruan Jun. Design of Real-Time Measurement of Atmospheric CO and CH4 Based on Tunable Diode Laser Spectroscopy System[J]. Acta Optica Sinica, 2015, 35(4): 0430001.