Turbid Optical Phantoms Using Microspheres: A Comprehensive Guide to Mixing Protocols and Optical Property Computation

Turbid optical phantoms play a crucial role in validating estimated optical properties across diverse applications, including medical imaging, surgical guidance, and photodynamic therapy. In this study, we discuss the benefits and limitations of both solid and liquid phantoms, emphasizing the precision in optical property adjustment offered by liquid phantoms. A detailed guideline for calculation of optical properties through Mie theory and corresponding implementation in a Monte Carlo (MC)-based light propagation model are provided. Finally, we introduce an open-source software tool designed to calculate the optical properties and provide a detailed mixing protocol. In addition, we describe experimental setups for reflectance and transmittance measurements, examining the effects of microsphere size, size distribution, and solid content on reflectance, and identify an optimal size range for achieving spectrally resolvable features that are most useful for calibration or fine-tuning of the MC light propagation model. This article includes examples of reflectance calibration and underscores the significance of accurate scattering phase function modeling in microsphere suspensions. This comprehensive guide aims to standardize the preparation and characterization of optical phantoms, enhancing their reliability and application across various optical fields.