Fig. 1. Schematic diagram of photoacoustic spectroscopy detection principle

Fig. 2. Schematic diagram of the absorption lines of SO₂ in the UV band and UV-LED spectral distribution

Fig. 3. Schematic diagram of SO₂ detection system based on UV photoacoustic spectroscopy

Fig. 4. The amplitude-frequency response of the measured photoacoustic spectroscopy system

Fig. 5. Relationship between photoacoustic response and SO₂/SF₆ mixed gas concentration

Fig. 6. Allan-Werle deviation analysis results. Inset：measured system noise