Reflection-enhanced differential laser-induced thermoelastic spectroscopy for gas detection

This paper presents the design and implementation of a reflection-enhanced differential laser-induced thermoelastic spectroscopy (RE-D-LITES) gas sensing system. A vacuum-packaged miniature quartz tuning fork (VP-MQTF) is employed as the sensing element, and a reflection-enhanced multi-pass optical configuration is introduced to increase laser interactions and enhance the signal amplitude. Meanwhile, a dual-VP-MQTF differential architecture is adopted to effectively suppress common-mode noise through synchronous dual-channel acquisition. Experimental results show that, compared with the multiple-excitation configuration, the proposed system achieves a 1.31-fold improvement in signal-to-noise ratio (SNR) and a minimum detection limit (MDL) of 0.95 ppm.