Fig. 1. Working schematic of the optical drop spectrometer

Fig. 2. Diagram raindrop imaging

Fig. 3. Diagram of particle velocity distortion effect. (a) Theoretical slice projection; (b) directly assembled original images

Fig. 4. Software design flowchart

Fig. 5. Raw image edge (a) and interpolated restored image edge (b)

Fig. 6. Diagram of experimental platform

Fig. 7. X-axis directional error map of 0.2 mm standard bar

Fig. 8. Error map in the measuring area of 0.2 mm standard gauge bar

Fig. 9. Schematic diagram of steel ball falling test (a) and laboratory device diagram (b)

Fig. 10. Diameter measurement error distribution diagram of steel ball with different diameters

Fig. 11. Velocity measurement error distribution diagram of steel ball with different diameters

Fig. 12. Distribution of measured values of droplet diameter (a) and velocity (b)