This paper presents an optimized T-type resonant photoacoustic (PA) cell for methane (CH₄) gas detection. The noise transmission coefficients and PA field distributions of the T-type resonant PA cell have been evaluated using the finite element method and thermoviscous acoustic theory. The optimized T-type resonant PA cell, together with a near-infrared (NIR) distributed feedback (DFB) laser source, a high-speed spectrometer and a fiber-optic acoustic sensor constitutes a PAS system for CH₄ detection. The sensitivity is measured to be 1.8 pm/ppm and a minimum detectable limit (MDL) of 9 parts per billion (ppb) can be achieved with an averaging time of 500 s. The optimized T-type longitudinal resonant PA cell features of high PA cell constant, fast response time and simple manufacturing process.

本文提出了一种用于甲烷（CH ₄ ）气体检测的优化T型谐振光声（PA）池。使用有限元方法和热粘性声学理论评估了 T 型谐振 PA 单元的噪声传输系数和 PA 场分布。优化的T型谐振PA单元与近红外（NIR）分布反馈（DFB）激光源、高速光谱仪和光纤声传感器一起构成了用于CH ₄检测的PAS系统。测量灵敏度为 1.8 pm/ppm，平均时间为 500 秒即可达到十亿分之 9 (ppb) 的最小可检测限 (MDL)。优化后的T型纵向谐振PA单元具有PA单元常数高、响应时间快、制造工艺简单的特点。