Development of a methane (CH₄) sensor system was reported based on a novel quartz-tuning-fork (QTF)-embedded, double-pass, off-beam quartz-enhanced photoacoustic spectroscopy (DP-OB-QEPAS). A simplified and accurate numerical model was presented to optimize the DP-OB-QEPAS spectrophone and to enhance the detection sensitivity. A compact and fiber-coupled acoustic detection module (ADM) with a volume of 3 × 2×1 cm³ and a weight of 9.7 g was fabricated. A continuous-wave distributed feedback diode laser was used to target the CH₄ absorption line at 6046.95 cm⁻¹. With the combination of wavelength modulation spectroscopy (WMS) and second harmonic (2f) detection technique, the CH₄ sensor system reveals a 1σ detection limit of 8.62 parts-per-million in volume (ppmv) for a 0.3 s averaging time with an optimized modulation depth of 0.26 cm⁻¹. The proposed CH₄ sensor shows a similar or even lower level in the normalized noise equivalent absorption coefficient (NNEA) (1.8 × 10⁻⁸ cm⁻¹∙W/√Hz), compared to previously reported QEPAS-based CH₄ sensors.

据报道，甲烷（CH ₄）传感器系统的开发基于一种新型的嵌入石英音叉（QTF），双通，离束的石英增强光声光谱法（DP-OB-QEPAS）。提出了一种简化而精确的数值模型，以优化DP-OB-QEPAS光谱仪并提高检测灵敏度。制作了体积为3×2×1 cm ³，重量为9.7 g的紧凑型纤维耦合声学检测模块（ADM）。使用连续波分布反馈二极管激光器将CH ₄吸收线对准6046.95 cm ^-1。结合波长调制光谱（WMS）和二次谐波（2 f）检测技术，CH ₄传感器系统在0.3 s的平均时间内显示出的1σ检测极限为8.62百万分之体积（ppmv），优化调制深度为0.26 cm ^-1。与先前报道的基于QEPAS的CH ₄传感器相比，拟议的CH ₄传感器在归一化噪声等效吸收系数（NNEA）（1.8×10 ^-8 cm ^-1 ∙W /√Hz）中显示出相似或更低的水平。