Research on the relationship between gas concentration detection and sound pressure based on photoacoustic spectroscopy

Based on the photoacoustic spectroscopy technology, this research designed a photoacoustic cell system for detecting gas concentration. By injecting a beam of periodically modulated light, the light reacts with the mixed gas. The gas molecules absorb the light and transition from the ground state to the excited state and then release heat. The periodically changing heat will generate periodically changing pressure, thereby generating sound waves. After receiving the sound wave through a microphone, the gas concentration can be calculated by analyzing the collected signal. This paper analyzes the principle of harmonic detection and analyzes the relationship between input thermal amplitude and sound pressure.