A long-term stable monitoring system for atmospheric carbon monoxide based on 2.3 μm laser absorption

Zhaowei Wang,Tong Sun,Jie Hu,Yanfang Li,Tingting Zhang,Tongyu Liu,Yubin Wei,Kenneth T V Grattan

doi:10.1088/1742-6596/1065/25/252017

Abstract

Recent progress in the development of an atmospheric carbon monoxide (CO) monitoring system using a ∼2.33 μm laser absorption sensor is reported. The principles of detection technology and the algorithms used for removing noise are discussed. In order to eliminate the cross interferences from the effects of CO2 and H2O in the atmosphere, a Distributed Feedback (DFB) laser at a specific wavelength of 2330.18 nm was employed in the system. The CO monitoring system demonstrated excellent accuracy and stability in long-term continuous monitoring. The results obtained have validated the use of such a CO monitoring approach in practical gas monitoring applications.

Highlights

As a colourless and odourless gas, carbon monoxide (CO) has been viewed as a silent killer due to its strong affinity for haemoglobin and it is known that exposure to the gas can seriously affect human health
A Tunable Diode Laser Absorption Spectroscopy (TDLAS)-based CO monitoring system using a 2.33 μm distributed feedback (DFB) laser is reported, based on the key principles of the detection technology discussed, together with algorithms used for removing noise, with the method employed for eliminating the cross interference from CO2 and H2O in the atmosphere
For the CO monitoring system, the interference from both CO2 and H2O are the major challenge in the atmospheres investigated

Summary

Introduction

As a colourless and odourless gas, carbon monoxide (CO) has been viewed as a silent killer due to its strong affinity for haemoglobin and it is known that exposure to the gas can seriously affect human health. An effective CO monitoring system is important for a range of practical safety-focused monitoring applications Monitors of this type can be developed by using Tunable Diode Laser Absorption Spectroscopy (TDLAS) technology, which has been widely used for CO gas sensing, taking advantage of the potential for real time monitoring, offering high sensitivity, long-term stability and excellent reliability. A fiber-based CO sensing system has been developed using a distributed feedback (DFB) diode laser in the wavelength region near 1.56 μm[1] It has been successfully applied in the field of coal mine safety, but compared to near-infrared diode lasers, a CO sensor using a diode laser around 2.3 μm can provide more sensitive detection because of the stronger first overtone band of CO near 2.33 μm. A TDLAS-based CO monitoring system using a 2.33 μm DFB laser is reported, based on the key principles of the detection technology discussed, together with algorithms used for removing noise, with the method employed for eliminating the cross interference from CO2 and H2O in the atmosphere

Principles of the detection system

Results and discussion

Conclusion