Measurement of Dispersion of the Refractive Index of Microscopic Volumes of the BSA Aqueous Solution Using an Interference Microscope

An interference microscopy-based method for measuring the refractive index of microscopic objects is considered. It is shown that of special interest is the analysis of the dispersion of the refractive index of small objects of biological fluids, which can make it possible to separate fluctuations of the size and the refractive index of the object in studying living cells by methods of phase microscopy. A method for measuring the dispersion of the refractive index of microscopic volumes of fluids using the MIA-1D automated interference microscope and a measuring cell with a microwell is described. An algorithm for processing the obtained images with the aim of calculating the refractive index is presented. The measurement results for the dispersion of the refractive index of bovine serum albumin are given. It is shown that the proposed method allows one to measure the refractive index of fluids in microscopic volumes up to four or five decimal places.