Theoretical research on a high Q factor elliptical differential photoacoustic resonator

The sensitivity of photoacoustic (PA) sensors strongly depends on the characteristic of PA cell. In the present paper, a novel elliptical differential PA cell was proposed to enhance the signal noise ratio of PA system. An acoustic characteristic mathematic model was built and the acoustic characteristic of PA cell was simulated with COMSOL software. The result shows that peak pressures would occur at the two ends of major axis with a π phase difference when the mixed modes in the cross section of elliptical cell have odd azimuthal nodes along the minor axis. When the half major axis is less than 4 cm, the resonant frequency could be greater than 10 kHz and the Q factor could achieve 1835. Differential detection of PA signal could be realized and the common mode environment noise would be suppressed effectively. The signal noise ratio can be enhanced and high sensitivity detection could be achieved with this high Q factor elliptical differential cell.