基于背景扣除的弱吸收信息精确提取方法研究

随着半导体器件的快速发展，基于分子振-转吸收光谱的研究日益深入，以可调谐半导体激光吸收光谱（Tunable Diode Laser Absorption Spectroscopy， TDLAS）为代表的检测技术取得巨大进步，应用领域进一步扩大，已有超过一千类仪器应用于连续监测以及过程控制，每年出售的气体检测仪器占据了红外气体传感检测仪器总数的5%以上，已实现不同领域组分浓度、温度、压力等参数的高精度探测。本文针对仪器开发领域目标吸收信息被完全覆盖的复杂应用环境，利用调制技术将吸收信息转移到高频部分，经过分通道背景扣除和谐波信号归一化处理提取吸收信息。以测量含硫天然气中微量H₂S为例，天然气中CH₄含量超过90%，目标组分H₂S的吸收信息被完全覆盖，将吸收信息转移到1 kHz频率，得到的谐波信号峰值与H₂S浓度呈正相关，线性参数达到0.999 9，实现了弱吸收信号的有效提取，从方法上验证了提取弱吸收信号的有效性，进一步扩展了光学气体传感的应用领域，为仪器开发提供技术保障。

Research on accurate extraction method of weakly absorbed information based on background deduction

With the rapid development of semiconductor devices, the research based on molecular vibration-rotation absorption spectroscopy has been deepened, significant progress has been made in detection methods represented by Tunable Diode Laser Absorption Spectroscopy (TDLAS), the application field has gradually expanded, and more than 1 000 instruments have been used in continuous emission monitoring and industrial process control and other fields, TDLAS-based gas detection instruments sold every year account for more than 5% of the total number of infrared gas sensing and detection instruments, and have achieved high-precision detection of parameters such as component concentration, temperature, and pressure in different fields. In this paper, in a complex application environment where the target absorption information in the instrument development field is completely covered, modulation technology is used to transfer the absorption information to the high-frequency part, and the absorption information is extracted through multi-channel background subtraction and harmonic signal normalization processing. Taking the measurement of trace H₂S in sulfur-containing natural gas as an example, when the CH₄ content in natural gas exceeds 90%, the absorption information of the target component H₂S is completely covered, and the absorption information is transferred to a frequency of 1 kHz. The peak value of the harmonic signal obtained is positively correlated with the H₂S concentration, with a linear parameter of 0.999 9, achieving effective extraction of weak absorption signals. The method verifies the effectiveness of extracting weak absorption signals. The effectiveness of extracting weak absorption signals is verified, which further expands the application field of optical gas sensing and provides technical support for instrument development.