THE SPATIAL VARIATION OF THE REFRACTIVE-INDEX IN BIOLOGICAL CELLS

With a phase microscope the phase shift of cells from type L 929 fibro blast and mitochondria from liver cells was measured. Compared to the total phase shift caused by the cell relative to vacuum (approximately 1400 nm) the single phase shift of the mitochondria (approximately 18 0 nm) is small. Only the nucleus and the membrane of the cell give a v isibly different phase shift relative to the mean value of the cell. T he Fraunhofer diffraction of the measured phase object is calculated. With a simplified scattering theory, i.e. Rayleigh-Gans scattering, di fferent phase objects are investigated and their differential cross se ction is discussed.