Shearing interferometry in polar coordinates

Shearing interferometers are developed that are able to display the radial component of a gradient with radial interference fringes and the azimuthal component of a gradient with circular interference fringes. Three concepts in particular are introduced. (i) A shearing interferometer is presented that has a constant azimuthal displacement between the interfering wave fronts. (ii) Emphasis is placed on the importance and convenience of using reference interference-fringe systems with radial and circular configurations to display shearing interferograms when the displacements between the wave fronts have polar-coordinate geometry. (iii) Computer-generated, holographic-type filters with circular carrier frequencies are shown to have properties of special value for shearing interferometry. Practical experimental realizations of the interferometers and techniques are discussed and results are shown.