Optical phantoms of varying geometry based on thin building blocks with controlled optical properties

Current innovations in optical imaging, measurement techniques, and data analysis algorithms express the need for reliable testing and comparison methods. We present the design and characterization of silicone elastomer-based optical phantoms. Absorption is included by adding a green dye and scattering by adding TiO or SiO particles. Optical coherence tomography measurements demonstrate a linear dependence of the attenuation coefficient with scatterer concentration in the absence of absorbers. Optical transmission spectroscopy of the nonscattering absorbing phantoms shows a linear concentration dependent absorption coefficient. Both types of samples are stable over a period of 6 months. Confocal microscopy of the samples demonstrates a homogeneous distribution of the scatterers, albeit with some clustering. Based on layers with thicknesses as small as 50 m, we make multifaceted structures resembling flow channels, (wavy) skin-like structures, and a layered and curved phantom resembling the human retina. Finally, we demonstrate the ability to incorporate gold nanoparticles within the phantoms. In conclusion, our phantoms are easy to make, are based on affordable materials, exhibit well-defined and controllable thickness, refractive index, absorption, and scattering coefficients, are homogeneous, and allow the incorporation of novel types of nanoparticle contrast agents. We believe our phantoms fulfill many of the requirements for an "ideal" tissue phantom, and will be particularly suited for novel optical coherence tomography applications.