Differential rotationally-shearing interferometer: Implementation concept

A new type of interferometer, a differential rotationally-shearing interferometer, differs from the traditional rotationally-shearing interferometer in that the angle of rotation is infinitesimal or, at least, very small. A differential rotationally-shearing interferometer may be used for the detection of wavefront asymmetry, even when its asymmetry is very small. We present an implementation concept for the differential rotationally-shearing interferometer, based on the Mach-Zehnder interferometer. One of the important advantages of the new interferometer is that the polarization problems do not arise do the small angle of rotation between the two wavefronts.