Fig. 1. Block diagram of optical particle counting module

Fig. 2. Schematic diagram of optical system. (a) XY section; (b) YZ section

Fig. 3. Defocusing spot of laser system

Fig. 4. Simulation of laser system. (a) Optical path simulation diagram of laser system; (b) irradiation map of photosensitive area

Fig. 5. Diagram of photoelectric signal conversion circuit

Fig. 6. Experimental setup of performance verification

Fig. 7. Diagram of particle pulse. (a) Scattering pulse of single particle; (b) scattering pulse of particle coincidence

Fig. 8. Experimental setup for concentration range measurement

Fig. 9. Concentration range test results

Fig. 10. Particle coincidence correction. (a) Fitting curve of correction factor; (b) corrected concentration error

Fig. 11. Comparison experiment. (a) Measurement results of indoor ambient air; (b) linear correlation coefficient of three devices

Fig. 12. Experimental setup of vehicle emission

Fig. 13. Vehicle emission experiment. (a) Measurement results of WLTP experiment; (b) linear correlation coefficient of measurement results