University of Oulu

I. Niskanen, J. Lauri, M. Yokota, R. Heikkilä, T. Hashimoto and T. Fabritius, "Determination of the Refractive Index of Particles Through the Immersion Solid Matching Method," in IEEE Transactions on Instrumentation and Measurement, vol. 70, pp. 1-5, 2021, Art no. 6000505, doi: 10.1109/TIM.2020.3016070

Determination of the refractive index of particles through the immersion solid matching method

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Author: Niskanen, Ilpo1; Lauri, Janne2; Yokota, Masayuki3;
Organizations: 1Faculty of Technology, Structures and Construction Technology, University of Oulu, FI-90014 Oulu, Finland
2Faculty of Information Technology and Electrical Engineering, Optoelectronics and Measurement Techniques Research Unit, University of Oulu, FI-90014 Oulu, Finland
3Department of Mechanical, Electrical and Electronic Engineering, Faculty of Science and Engineering, Shimane University, Shimane 690-8504, Japan
Format: article
Version: accepted version
Access: open
Online Access: PDF Full Text (PDF, 1.1 MB)
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Language: English
Published: Institute of Electrical and Electronics Engineers, 2021
Publish Date: 2021-03-29


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 (CaF 2 ) particles with a varnish immersion liquid. The RI value of CaF 2 was obtained to be consistent with the literature values, thus indicating the proper functioning of the proposed procedure.

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Series: IEEE transactions on instrumentation and measurement
ISSN: 0018-9456
ISSN-E: 1557-9662
ISSN-L: 0018-9456
Volume: 70
Pages: 1 - 5
DOI: 10.1109/TIM.2020.3016070
Type of Publication: A1 Journal article – refereed
Field of Science: 112 Statistics and probability
216 Materials engineering
114 Physical sciences
213 Electronic, automation and communications engineering, electronics
Funding: This work was supported by Business Finland (4294/31/2018) and Academy of Finland’s FIRI funding (grant no. 320017).
Academy of Finland Grant Number: 320017
Detailed Information: 320017 (Academy of Finland Funding decision)
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