Fig. 1. Schematic diagram of particle detection by light-blockage method

Fig. 2. Coaxial lighting system and cross-axis lighting system

Fig. 3. A brief diagram of the experimental apparatus

Fig. 4. A comparison of transmission signal before and after filtering

Fig. 5. A comparison of scattered signal before and after filtering

Fig. 6. Simultaneous acquisition of signal by light-blockage and angle scattering

Fig. 7. The CCD camera captures the passing of a single particle by using a beam of light

Fig. 8. Transmission of standard particles with different particle sizes

Fig. 9. Fitting curve for calibration of standard particle signals

Fig. 10. Images and particle-size distributions by light-blockage measurements

Fig. 11. Comparison of measurement and fitting values of standard particle signals

Fig. 12. Measured signal and size distribution of mixed particles