Abstract
We have been studying a continuous measurement system for gas concentration by means of a photoacoustic effect, which is observed as photoacoustic energy when gas molecules are excited by laser beam energy.
In this paper, the photoacoustic properties of a newly designed photoacoustic cell are described. The structures of photoacoustic cell plays an impdrtant role on noise characteristics in the photoacoustic measurement system using a CO2 laser. In order to obtain a better signal to noise ratio, configuration of cells and intensitiy of photoacoustic signals were examined experimentally based on data using a non-resonance single-tube type cell as a standard cell.
The results showed that a double-tube cell had a high photoacoustic isolation effect for external noises. Futhermore, the optimal condition for obtaining a high-intensity photoacoustic signal was ascertained by spectrum analysis of the resonant frequency of cells.
Thus, it was confirmed that a resonance double-tube type cell retained a better SN ratio, and was appropriate for the photoacoustic measurement system for gas concentration useing CO2 laser.
