Measurement of the refractive index of biological tissues of the head using OCT and a multi-wavelength refractometer

Research and development in the field of laser biomedical diagnostics and therapy determine the interest in quantitative assessment of the optical properties of biological tissues, in particular the phase and group refractive index (RI). Knowledge of the optical dispersion dependencies of head tissues in a wide spectral range is necessary for the development of non-invasive methods for the diagnosis and treatment of brain diseases. In this regard, in this work, RI measurements were performed for rat head tissue samples (scalp, skull bone, dura mater, gray and white matter of the brain) ex vivo in the visible/near IR spectral range using optical coherence tomography (OCT) and a multi-wave Abbe refractometer for a number of laser wavelengths: 480, 486, 546, 589, 644, 656, 680, 800, 930, 1100, 1300 and 1550 nm. The phase RI values measured using a refractometer and determined from dispersion measurements and group RI at a central wavelength of 930 nm of an OCT system with a band of 100 nm were compared. The obtained RI values are in good agreement with known literature data.