Fig. 1. The basic structure of AOTF

Fig. 2. Wave vector matching condition

Fig. 3. Overall architecture of AOTF spectral imaging system

Fig. 4. Optical components inside the spectral imaging system

Fig. 5. Imaging results before and after electric drive loading

Fig. 6. Imaging effect after the light intensity is subtracted

Fig. 7. Sample gas test device

Fig. 8. Spectrum extraction method (a) and results (b)

Fig. 9. Concentration measurement results of nitrogen dioxide sample gas with calibration concentration of 9.05 × 10¹⁷ molecule/cm²

Fig. 10. Correspondence between measured concentration value and given concentration value