Authors

Abstract

A methane gas detection system has been developed based on the infrared absorption method. The system can be deployed in dry rice field for real-time detection. It consists of self-developed circuits and essential optical parts. A distributed feedback laser has been chosen as the optical source of the system. Hollow-core photonic crystal fibre is also applied as a part of the gas cell. The major circuit boards include laser driver circuit, laser temperature control circuit, digital lock-in amplifier circuit and linear power circuit. The laser diode can be effectively controlled by using the above circuits. The laser driving current step is 1 mA and the temperature fluctuation is less than ± 0.02 ℃. Based on the TDLAS technique, spectroscopy test shows that the proposed laser driving circuits has accurate control capability. The detection error is about 2.3% by performing the full-scale detection experiments. Further gas detection experiments using standard gas under 600 ppm also demonstrate the effectiveness and stability of the proposed system. By replacing the optical source and essential driving circuits of the system, the system can be applied to detect other trace gases.

Abstract in Chinese

开发了一种基于红外吸收法的甲烷气体检测系统。该系统可以部署在旱稻田中进行实时气体检测。它由自主开发的电路和相关光学部件组成，包括分布式反馈激光器和空心光子晶体光纤。系统中主要电路板包括激光驱动电路、激光温度控制电路、数字锁向放大器电路和线性电源电路。使用上述电路可以有效地控制激光二极管。激光驱动电流步长为 1 mA，其温度波动可以限制在 ±0.02℃的范围内。基于 TDLAS 技术，光谱测试表明，所提出的激光驱动电路具有精确的控制能力。通过进行全量程的气体检测实验，检测误差约为 2.3%。进一步使用 600 ppm 以下的标准气体进行气体检测实验也证明了所提出系统的有效性和稳定性。通过更换系统的光源和基本驱动电路，该系统可以应用于其他痕量气体的检测。