基于TDLAS烟道气在线检测系统的降噪技术

可调谐激光光谱（TDLAS）技术利用激光管的波长扫描实现痕量气体吸收曲线的二次谐波检测，具有响应时间短、检测灵敏度高、精度高等优点。但实际应用条件分析结果表明，烟道气在线检测中存在外界环境和系统本身引入的噪声。为了实现TDLAS检测方法的高精度、高灵敏度等优势，本文提出在检测系统中加入温度反馈，以减少高温环境带来的干扰，设计并采用双光路扣除背景，消除颗粒物及背景吸收干扰以及采用对激光管驱动电流进行高频调制来抑制系统噪声等3条主要的降噪途径。理论分析表明，这些措施可以降低环境干扰及系统噪声影响，有效提高检测精度。

Noise Reduction Technology of In-situ Gas Monitoring System Based on TDLAS

As a new trace gas detection technique, tunable diode laser absorption spectroscopy （TDLAS） can realize the second-harmonic detection of the trace gases absorption curve by using the wavelength scanning of the laser, it has the following advantages such as short respond time, high sensitivity and high precision and so on. But the practical application condition results indicate that environment interference and system noise can＇t be ignored in the in-situ gas monitoring system. The three major noise reduction channels such as adding temperature feedback in the detection system to reduce interference from high-temperature environment, design and use a dual optical path of background deduction to eliminate particulate matter and background absorption interference, using the application of the laser drive current to carry out high-frequency modulation system to suppress noise are introduced in this paper. Theory analysis shows that these measures can reduce the environmental interference and system noise, and also can improve detection accuracy effectively.