Determination of the Refractive Index of Particles Through the Immersion Solid Matching Method

We describe a new measurement technique to determine the refractive index (RI) of solid particles by monitoring the simultaneous scattering of light from suspension with a camera and the value of the RI with a refractometer. Our immersion solid matching method is based on the solidification process of the liquid continuously changing the RI as a function of time. The principle of the determination is based on finding the RI matching point of the particle and the liquid during the solidification. The traditional liquid immersion method is based on a set of immersion liquids with different refractive indices, while the proposed method requires only a small amount of a single immersion liquid. The method was tested using calcium fluoride (CaF2) particles with a varnish immersion liquid. The RI value of CaF2 was obtained to be consistent with the literature values, thus indicating the proper functioning of the proposed procedure.

[1]  Gaël Epely-Chauvin,et al.  Refractive-index and density matching in concentrated particle suspensions: a review , 2011 .

[2]  Thomas Wriedt,et al.  Refractive-index measurements in the near-IR using an Abbe refractometer , 1997 .

[3]  H. Kano,et al.  Refractive index measurement of nanoparticles by immersion refractometry based on a surface plasmon resonance sensor , 2016 .

[4]  O. Heavens.  Handbook of Optical Constants of Solids II , 1992 .

[5]  A. García-Valenzuela,et al.  Determination of refractive index, size, and concentration of nonabsorbing colloidal nanoparticles from measurements of the complex effective refractive index. , 2014, Optics letters.

[6]  K. Hibino,et al.  Immersion liquid techniques in solid particle characterization: A review. , 2016, Talanta.

[7]  John G. Webster,et al.  The Measurement, Instrumentation and Sensors Handbook , 1998 .

[8]  W. Pisarski,et al.  Sol-Gel Glass-Ceramic Materials Containing CaF2:Eu3+ Fluoride Nanocrystals for Reddish-Orange Photoluminescence Applications , 2019 .

[9]  H. Liimatainen,et al.  Monitoring drying process of varnish by immersion solid matching method , 2019, Progress in Organic Coatings.

[10]  P. Weidler,et al.  Determination of the refractive index of particles in the clay and sub-micrometer size range , 2007 .

[11]  G. Meeten,et al.  Refractive index measurement of absorbing and turbid fluids by reflection near the critical angle , 1995 .

[12]  Uddin M Jalal,et al.  Histogram analysis for smartphone-based rapid hematocrit determination. , 2017, Biomedical optics express.

[13]  Essam E. Hinnawi.  Methods in chemical and mineral microscopy , 1966 .