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 (C2H2) gas detection system based on PA spectroscopy. Experimental results show that the minimum detectable limit of C2H2 is calculated to be 0.70 parts per billion (ppb), which is lower than the traditional H-type PA cell.