A four-off-beam acoustic micro-resonator (AmR) structure is proposed to improve the photoacoustic signal intensity in quartz-enhanced photoacoustic spectroscopy (QEPAS) for trace gas sensing. Two vertical-array-based double-off-beam AmR structures are arranged on each side of the quartz tuning fork (QTF) horizontally to construct a four-off-beam AmR structure using a rectangular prism. This QEPAS scheme based on the four-off-beam AmR is evaluated in the water-vapor detection of air at normal atmospheric pressure and room temperature (27 °C). Comparing with the bare QTF scheme, the new QEPAS configuration enhances the photoacoustic spectroscopy signal by a factor of 25.84 times, achieving a minimum detection limit of 278 ppbv with a normalized noise equivalent absorption coefficient of 1.27 × 10−9 W/Hz1/2 in water vapour detection at a wavelength of 1368.597 nm.

中文翻译：

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基于四离束声微谐振器的石英增强光声光谱

提出了一种四离束声微谐振器 (AmR) 结构，以提高用于痕量气体传感的石英增强光声光谱 (QEPAS) 中的光声信号强度。两个基于垂直阵列的双离束 AmR 结构水平排列在石英音叉 (QTF) 的每一侧，以使用直角棱镜构建四离束 AmR 结构。这种基于四离束 AmR 的 QEPAS 方案在正常大气压和室温 (27 °C) 下的空气水蒸气检测中进行了评估。与裸 QTF 方案相比，新的 QEPAS 配置将光声光谱信号增强了 25.84 倍，实现了 278 ppbv 的最低检测限，归一化噪声等效吸收系数为 1。