Integration of T-type half-open photoacoustic cell and fiber-optic acoustic sensor for trace gas detection

We present a novel T-type half-open resonant photoacoustic (PA) cell for trace gas detection. The T-type PA cell has just one buffer volume, and a fiber-optic acoustic sensor is placed at one end of the resonator. Compared with the conventional H-type PA cell, the first-order resonant frequency of the T-type PA cell is reduced by half and the PA signal is enhanced with the same resonator. The T-type resonant PA cell was used in acetylene (C 2 H 2 ) gas detection system based on PA spectroscopy. Experimental results show that the minimum detectable limit of C 2 H 2 is calculated to be 0.70 parts per billion (ppb), which is lower than the traditional H-type PA cell.