TY - JOUR

T1 - Retrieving refractive index of single spheres using the phase spectrum of light-scattering pattern

AU - Romanov, Andrey V.

AU - Maltsev, Valeri P.

AU - Yurkin, Maxim A.

PY - 2023/6

Y1 - 2023/6

N2 - We analyzed the behavior of the complex Fourier spectrum of the angle-resolved light scattering pattern (LSP) of a sphere in the framework of the Wentzel–Kramers–Brillouin (WKB) approximation. Specifically, we showed that the phase value at the main peak of the amplitude spectrum almost quadratically depends on the particle refractive index, which was confirmed by numerical simulations using both the WKB approximation and the rigorous Lorenz–Mie theory. Based on these results, we constructed a method for characterizing polystyrene beads using the main peak position and the phase value at this point. We tested the method both on noisy synthetic LSPs and on the real data measured with the scanning flow cytometer. In both cases, the spectral method was consistent with the reference non-linear regression one. The former method leads to comparable errors in retrieved particle characteristics but is 300 times faster than the latter one. The only drawback of the spectral method is a limited operational range of particle characteristics that need to be set a priori due to phase wrapping. Thus, its main application niche is fast and precise characterization of spheres with small variation range of characteristics.

AB - We analyzed the behavior of the complex Fourier spectrum of the angle-resolved light scattering pattern (LSP) of a sphere in the framework of the Wentzel–Kramers–Brillouin (WKB) approximation. Specifically, we showed that the phase value at the main peak of the amplitude spectrum almost quadratically depends on the particle refractive index, which was confirmed by numerical simulations using both the WKB approximation and the rigorous Lorenz–Mie theory. Based on these results, we constructed a method for characterizing polystyrene beads using the main peak position and the phase value at this point. We tested the method both on noisy synthetic LSPs and on the real data measured with the scanning flow cytometer. In both cases, the spectral method was consistent with the reference non-linear regression one. The former method leads to comparable errors in retrieved particle characteristics but is 300 times faster than the latter one. The only drawback of the spectral method is a limited operational range of particle characteristics that need to be set a priori due to phase wrapping. Thus, its main application niche is fast and precise characterization of spheres with small variation range of characteristics.

KW - Inverse problem

KW - Light scattering

KW - Refractive index

KW - Spectral method

UR - https://www.scopus.com/inward/record.url?eid=2-s2.0-85146865896&partnerID=40&md5=fa0d33dca4071a858db7185b56652c26

UR - https://www.mendeley.com/catalogue/c14047ce-4c3a-34b7-be4d-910af850e7bb/

U2 - 10.1016/j.optlastec.2023.109141

DO - 10.1016/j.optlastec.2023.109141

M3 - Article

VL - 161

JO - Optics and Laser Technology

JF - Optics and Laser Technology

SN - 0030-3992

M1 - 109141

ER -