Palm-sized methane TDLAS sensor based on a mini-multi-pass cell and a quartz tuning fork as a thermal detector

A palm-sized methane (CH4) tunable diode laser absorption spectroscopy (TDLAS) sensor is reported, in which a quartz tuning fork (QTF) is used as a thermal detector, working together with a mini-multi-pass cell (mini-MPC) to compose a gas detection module (GDM) with a compact dimension of 78 mm x 40 mm x 40 mm. A 1.65 mu m near-infrared distributed feedback (DFB) laser is installed in the sensor for CH4 detection. A minimum detection limit (MDL) of 52 ppb is achieved at an integration time of 300 ms, corresponding to a normalized noise equivalent absorption coefficient (NNEA) of 2.1x10(-8) cm(-1)W/Hz(1/2). A seven-day continuous monitoring of atmospheric CH4 concentration is implemented to verify the sensor's long-term stability. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

This study presents a palm-sized methane (CH4) tunable diode laser absorption spectroscopy (TDLAS) sensor with compact dimensions and high sensitivity for detecting extremely low concentrations of methane in a short time. The sensor utilizes advanced technology to demonstrate its long-term stability and reliability through continuous monitoring of atmospheric CH4 concentration for seven days.