Reflectance confocal microscopy of optical phantoms

A reflectance confocal scanning laser microscope (rCSLM) operating at 488-nm wavelength imaged three types of optical phantoms: (1) 100-nm-dia. polystyrene microspheres in gel at 2% volume fraction, (2) solid polyurethane phantoms (INO Biomimic™), and (3) common reflectance standards (Spectralon™). The noninvasive method measured the exponential decay of reflected signal as the focus (z_f) moved deeper into the material. The two experimental values, the attenuation coefficient μ and the pre-exponential factor ρ, were mapped into the material optical scattering properties, the scattering coefficient μ_s and the anisotropy of scattering g. Results show that μ_s varies as 58, 8-24, and 130-200 cm^-1 for phantom types (1), (2) and (3), respectively. The g varies as 0.112, 0.53-0.67, and 0.003-0.26, respectively.