The relationship between viscosity, elasticity and plastic strength of soft materials as illustrated by some mechanical properties of flour doughs, I

Abstract

Some of the drawbacks of conventional phase contrast microscopy are enumerated and the desirability of an interferometer microscope is indicated. A number of existing ways of achieving this are described, together with their merits and drawbacks. A new type of interferometer microscope which avoids some of these disadvantages is described, together with its operational procedure. The conditions covering coherence in the object plane are investigated and a simple approximation for evaluating the coherence is derived. An elementary discussion of contrast arising from phase or amplitude objects is given, and a number of experimental results are presented as photo-micrograms. Finally, a method for the accurate measurement of the optical thickness of an object is described, with the results of a determination of the refractive index of the cytoplasm of epithelial cells.