A method for measuring small retardations of structures in living cells

Abstract A new half shade method for measuring retardations in optically complicated structures is presented. By using a polarization microscope with an extinction of 105, a retardation as small as a tenth of a mμ (in objects not larger than a micron in diameter) can be measured very rapidly by this method. Especially important is the fact that such measurements can easily be made without injury, directly upon the living cells.