Determination of refractive index, size, and solid content of monodisperse polystyrene microsphere suspensions for the characterization of optical phantoms

Naglič, Peter (author), Zelinskyi, Yevhen (author), Likar, Boštjan (author), Bürmen, Miran (author)

Monodisperse polystyrene microspheres are often utilized in optical phantoms since optical properties such as the scattering coefficient and the scattering phase function can be calculated using the Mie theory. However, the calculated values depend on the inherent physical parameters of the microspheres which include the size, refractive index, and solid content. These parameters are often provided only approximately or can be affected by long shelf times. We propose a simple method to obtain the values of these parameters by measuring the collimated transmission of polystyrene microsphere suspensions from which the wavelength-dependent scattering coefficient can be calculated using the Beer-Lambert law. Since a wavelength-dependent scattering coefficient of a single suspension is insufficient to uniquely derive the size, refractive index and solid content by the Mie theory, the crucial and novel step involves suspending the polystyrene microspheres in aqueous sucrose solutions with different sucrose concentrations that modulates the refractive index of the medium and yields several wavelength-dependent scattering coefficients. With the proposed method, we are able to obtain the refractive index within 0.2% in the wavelength range from 500 to 800 nm, the microsphere size to approximately 15 nm and solid content within 2% of their respective reference values.

• Language: English
• Keywords: forward scattering, Mie theory, multiple scattering, refractive index, scattering measurement
• Work type: Article
• Typology: 1.01 - Original Scientific Article
• Organization: FE - Faculty of Electrical Engineering
• Publication status: Published
• Publication version: Version of Record
• Year: 2020
• Number of pages: Str. 1901-1918
• Numbering: Vol. 11, no. 4, art. 387619
• PID: 20.500.12556/RUL-128815
• UDC: 535
• ISSN on article: 2156-7085
• DOI: 10.1364/BOE.387619
• COBISS.SI-ID: 12953940

Copyright

V članku navedeno: "© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement"; s povezavo https://www.osapublishing.org/library/license_v1.cfm. (3. 8. 2021)

• Publication date in RUL: 03.08.2021

Record is a part of a journal

• Title: Biomedical optics express
• Shortened title: Biomed. opt. express
• Publisher: Optica
• ISSN: 2156-7085
• COBISS.SI-ID: 24857383

Secondary language

• Language: Slovenian
• Keywords: usmerjeno sipanje, teorija Mie, večkratno sipanje, lomni količnik, meritve sipanja