Integrated Multiexcitation Dual-Spectroscopy Detection Technique Based on QEPTS and QEPAS

A multi-excitation quartz enhanced photoacoustic spectroscopy (QEPAS) and photothermal spectroscopy integrated detection structure is introduced. A laser beam incident at a certain angle is obtained by tilting the fiber optic collimator, and two plane mirrors are placed on both sides of the quartz tuning fork (QTF). This causes the laser beam to retrace several times between the arms of the QTF. The metal layer in the middle of the bottom of the QTF is removed by chemical etching for the laser beam through the bottom of the QTF, so that the laser beam can travel back and forth between the two plane mirrors at the bottom of the QTF. This structure achieves multiple excitation on a single QTF, and simultaneously realizes a single QTF dual-spectroscopy detection. Compared with the traditional QEPAS measurement method, the detection technology improves the signal strength by 11.1 times, its minimum detection limit is 1.56 ppmv.