We described a new method to determine tissue density using a modified interferometric scattering experiment.1 The
most critical aspect of the tissue characterization problem is calibration of experimental measurements. During the
calibration step, the absorption and scattering indices βa and βsc are determined as a function of concentration, for each
material or tissue of interest, using a set of containers to vary travel distance D. It is assumed that linear scattering
coefficient, ksc (absorption coefficient, αa), is proportional to number of scattering particles per unit volume, or particle
concentration, c, in [ml/l]. Attenuation is proportional to concentration of scattering/absorption centers and sample
length. The calibration method relates the fringe irradiance (power modulation in one interferometer arm) with the
sample concentration under controlled conditions.