共光声池腔芯轴型空气衬底光纤麦克风

声传感器和光声池是激光光声光谱技术的核心组件。结合光纤迈克耳孙干涉仪、相位载波解调技术和纵向共振光声池,提出一种共光声池腔的芯轴型空气衬底光纤麦克风。光纤麦克风中的铜毛细管被用作光声池的共振腔,传感臂由10 m长的超细光纤缠绕在铜毛细管上构成,参考臂为5 cm长的短臂且已进行隔声隔振处理。基于结构共振频率稳定的特点,优化光纤麦克风的共振频率,使其略低于光声池的一阶纵向共振频率,以实现准双共振。实验结果表明,麦克风在共振频率为1443 Hz处的最小可检测声压为0.69μPa√Hz。在1 kHz处,声压电压响应线性度为99.98%(5 mPa~3 Pa),动态范围为112.52 dB。该光纤麦克风适用于高温、易爆和高电磁干扰等特殊环境下痕量气体的高精度检测。

Air-Backed Mandrel Fiber Optic Microphone with a Resonant Photoacoustic Tube

Acoustic sensor and photoacoustic cell are key components of laser-based photoacoustic spectroscopy.In this paper,we proposed an air-backed mandrel fiber optic microphone with a resonant photoacoustic tube,combining the technologies of fiber Michelson interferometer,phase generated carrier demodulation,and longitudinal resonant photoacoustic cell.In the microphone,we fabricated a sensing arm by wrapping a 10-meter ultra-thin single-mode fiber on a copper capillary tube that was also utilized as the resonant tube of the photoacoustic cell.Besides,a 5-cm reference arm has been isolated from sound and vibration.Furthermore,the resonant frequency of the microphone was designed to be slightly lower than the first-order longitudinal resonant frequency of the photoacoustic cell to achieve quasi-double resonance as the resonant frequency of the microphone was stable.The experimental results show that the minimum resolution is 0.69μPa√Hz at the resonant frequency of 1443 Hz,and the linearity of acoustic pressure and voltage response is 99.98%(5 mPa-3 Pa)with a dynamic range of 112.52 dB at 1 kHz.In conclusion,the microphone can be applied for trace gas detection in high-temperature,explosive,or high-electromagnetic-interference environments.