Fig. 1. Principle of IPI

Fig. 2. Variation curve of measurable particle size range with object distance. (a) Curve of maximum measurable particle size with object distance; (b) curve of minimum measurable particle size with object distance

Fig. 3. Experimental system and result analysis. (a) Principle of experimental system; (b) fringe images collected by experimental system; (c) function between defocusing distance g and ∆l

Fig. 4. Images in different fields of view of IPI system. (a) 435.9 mm≤z_o<442.1 mm; (b) z_o≤435.9 mm; (c)light intensity of P=0 and P=1, d=51 μm and d=110 μm

Fig. 5. Processing results of fringe. (a) (b) M₁ particle and N₁ particle in Fig. 4 (a); (c) particle M₂ in Fig. 4 (b)