Abstract
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.
Highlights
Optical phantoms are often utilized for calibration of optical systems [1] and validation of inverse models for estimation of optical properties [2]
Rmeasured RMC, d = 1.007 μm RMC, d = 1.021 μm RMC, d = 1.050 μm RMC, d = 1.070 μm Characterization of Suspensions of polystyrene microspheres (SPMs) in terms of refractive index, size and solid content is important for accurate calculation of optical properties of SPM-based turbid phantoms
We have proposed a simple method that is based on collimated transmittance measurements of SPMs diluted by different sucrose solutions
Summary
Optical phantoms are often utilized for calibration of optical systems [1] and validation of inverse models for estimation of optical properties [2]. The optical properties of other phantoms have to be measured by a well-validated optical modality that is not readily available in every laboratory or institution [4] These modalities can introduce bias and uncertainty into the estimated values of optical properties. Even though the optical properties of SPMs can be accurately derived from the Mie theory, the accuracy of calculated values still depends on the inherent physical properties of the microspheres Among these properties is the size distribution of the microspheres, which is for commercially available SPMs usually modeled by a Gaussian distribution with supplier-provided mean and standard deviation of the diameter. This information is commonly given by suppliers as the solid content of suspension, from which the number density can be calculated
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
