Fig. 1. Schematic of gas-solid two-phase optical sample cell

Fig. 2. Simulation of the multi-pass construction and the irradiance on the cavity mirror

Fig. 3. Schematic of the experimental setup

Fig. 4. Processing results of gas absorption spectra in particulate environment. (a) Detected spectrum signal; (b) particle extinction signal and gas absorption signal

Fig. 5. Measured C₂H₂ direct absorption spectra at different volume fractions and different temperatures. (a) Direct absorption spectra for different C₂H₂ volume fractions (0.2%-1.0%) at the temperature of 900 K; (b) direct absorption spectra for 0.4% C₂H₂ volume fraction in the temperature range of 500-1000 K

Fig. 6. Comparison of the measured and nominal values of C₂H₂ volume fraction and temperature. (a) Comparison of the measured and nominal C₂H₂ volume fractions at different temperatures; (b) comparison of the measured and nominal temperatures