Mei Huaiyu, Wang Gaoxuan, Xu Yinghe, He Haijie, Yao Jun, He Sailing
Centre for Optical and Electromagnetic Research, Ningbo Innovation Center, College of Optical Science and Engineering, Zhejiang University, Hangzhou 310058, China.
Taizhou Hospital, Zhejiang University, Taizhou, China.
Photoacoustics. 2024 Jul 30;39:100635. doi: 10.1016/j.pacs.2024.100635. eCollection 2024 Oct.
Hydrocarbon gas sensing is a challenging task using laser absorption spectroscopy due to the complex and broad structure of absorption lines. This application requires quick, accurate and highly sensitive detection of hydrocarbon gases concentrations. In this paper, a compact photoacoustic spectrophone was developed to simultaneously measure methane, propane and isobutane. This spectrophone uses wavelength modulation spectroscopy (WMS) with a single acoustic resonator and a single DFB laser emitting at 3368 nm, which greatly reduces the system complexity without using time-division multiplexing technology for multi-gas sensing. Due to the complex and broadband absorption of hydrocarbon gases, a novel signal processing method based on multilinear regression with Ridge regression (MLR-RG) is proposed to reduce the measurement error caused by the nonlinearity of spectra signal. For single gas measurement, the detection limits of methane, propane, and isobutane are determined to be 828 ppb, 419 ppb, and 619 ppb (SNR 1, integration time 20 s), respectively. For simultaneous multi-gas sensing in a gaseous mixture, the detection limits of propane and isobutane are determined to be 7 ppb, 68 ppb with an integration time of 860 s, 460 s, respectively. The measurement accuracy of propane and isobutane using MLR-RG is higher than that of ordinary least squares regression and partial least squares regression by 75% and 60%, respectively. The proposed algorithm based on MLR-RG provides a promising approach to process the broad overlapping absorption spectra for accurately retrieving hydrocarbon gases concentrations.
由于吸收线结构复杂且带宽较宽，利用激光吸收光谱法进行烃类气体传感是一项具有挑战性的任务。该应用需要快速、准确且高度灵敏地检测烃类气体浓度。本文研制了一种紧凑型光声光谱仪，用于同时测量甲烷、丙烷和异丁烷。该光谱仪采用波长调制光谱技术（WMS），配备单个声学谐振器和一个发射波长为3368 nm的单DFB激光器，无需使用时分复用技术进行多气体传感，大大降低了系统复杂性。由于烃类气体具有复杂的宽带吸收特性，提出了一种基于岭回归的多线性回归（MLR-RG）新型信号处理方法，以减少光谱信号非线性引起的测量误差。对于单一气体测量，甲烷、丙烷和异丁烷的检测限分别确定为828 ppb、419 ppb和619 ppb（信噪比为1，积分时间为20 s）。对于气态混合物中的同时多气体传感，丙烷和异丁烷的检测限分别确定为7 ppb、68 ppb，积分时间分别为860 s、460 s。使用MLR-RG对丙烷和异丁烷的测量精度分别比普通最小二乘回归和偏最小二乘回归高75%和60%。所提出的基于MLR-RG的算法为处理宽重叠吸收光谱以准确反演烃类气体浓度提供了一种有前景的方法。
