Fig. 1. Principle of phase difference method. (a) Cuvette structure; (b) rays of phase difference method

Fig. 2. Lightpath schematic of single-wavelength digital holographic microscopic system

Fig. 3. Holograms and phases of PE, PP, and PS particles in naphthalene solution. (a)(b) Digital hologram and phase image of PE particle; (c)(d) digital hologram and phase image of PP particle; (e)(f) digital hologram and phase image of PS particle

Fig. 4. Data density distribution of refractive index of naphthalene solution during adsorption

Fig. 5. Adsorption kinetics results of naphthalene by microplastics at 25 ℃ (pH=7.0). (a) Results from fluorescence spectrophotometry; (b) results from phase difference method