Abstract: A new type of ellipsoidal resonant photoacoustic cell is proposed. The finite element analysis software is used to establish the acoustic characteristic model of the cell, and the resonance frequency, the sound pressure distribution in the resonant cavity of the novel photoacoustic cell are calculated. According to the distribution of the absorption line of acetylene gas in the near infrared region, 1532.83 nm is selected as the measurement line of acetylene, and a tunable distributed feedback (DFB) semiconductor laser is selected as the light source. Fabry-Perot (F-P) fiber optic acoustic sensor is used to collect the sound pressure signal, and the performance indicators of the ellipsoidal photoacoustic cell are tested. The experimental results show that the signal-to-noise ratio of the ellipsoidal photoacoustic cell is 34, the detection limit sensitivity reaches 1:47 × 10−9, and the quality factor is 45.5. So it seems that the sensitivity of the system and the performance have been improved significantly by using the proposed structure, which helps to improve the sensitivity of photoacoustic spectroscopy for trace gas detection.

Key words: spectroscopy, ellipsoidal resonant photoacoustic cell, photoacoustic spectroscopy, C2H2; sensitivity