Highly sensitive and full range laser methane gas detector based on automatic wavelength-switching algorithm

Abstract

To address the challenge of achieving both high sensitivity and a wide dynamic range in methane (CH₄) leakage detection for municipal gas and petrochemical industries, this study presents a highly sensitive, full-range CH₄ detector based on tunable diode laser absorption spectroscopy (TDLAS). The detector integrates direct absorption spectroscopy (DAS) and wavelength modulation spectroscopy (WMS) techniques. An automatic wavelength-switching algorithm is implemented to alternate between strong and weak absorption lines via the DAS method, while the WMS technique is employed for accurate gas concentration measurement. The developed CH₄ gas detector demonstrates a detection limit as low as 0.169 ppm and a dynamic range extending up to 100 % volume concentration, with a linear regression coefficient (R²) of 0.9996 across the full range. Compared to existing detectors, this approach achieves substantial advancements in sensor size, effective optical path length, and detection sensitivity, fulfilling the requirements for portable, high-performance gas detection equipment.