Radial- and circular-fringe interferograms

New types of interference-fringe configurations in displays of interferograms are introduced. In particular, two types that show the data directly in polar coordinates appear attractive. These are radial-and circular-fringe interferograms. Several ways are described to transform the reference wave in a conventional interferometer so that a new type of interferogram is obtained. Feasibility experiments have been promising. Spiral-fringe interferograms have also been realized.