Improved IP-QEPAS sensor based on cylindrical cavity enhancement

摘要

In this paper, a cylindrical cavity based in-plane quartz-enhanced photoacoustic spectroscopy (IP-QEPAS) was demonstrated for the first time. The cylindrical cavity was designed by theoretical mode and used as a resonator to improve the strength of acoustics wave. The relationship between radius of cylindrical cavity and acoustic pressure was analyzed theoretically. After adding cylindrical cavities, due to the coupling effect, both resonance frequency and Q-factor of quartz tuning fork (QTF) were decreased. The second harmonic (2f) signal amplitude was measured at an optimal laser wavelength modulation depth of 0.446 cm-1. A 1.57 times improvement of 2f signal amplitude was realized when a cavity with radius of 6.00 mm was added. The experimental results agreed with the theoretical analysis. The cylindrical cavity based IP-QEPAS sensor performance can be further improved when a QTF with large prongs length is used.