Formation of the image of a microstep profile in a heterodyne differential-phase microscope

A theory of the formation of images of microscopic objects of arbitrary shape in a laser heterodyne differential-phase microscope is developed. This theory is used to propose a method for measuring the parameters of step-like microscopic objects with ultrahigh resolution. The experimental results show that this method can be used to analyse deep (h > λ) amplitude—phase steps with the lateral definition better than 0.1 μm.