Abstract

Various optical arrangements to obtain radial shear in a converging beam of laser light are presented. The interferometer is made of a cube-type beam splitter such that two opposite surfaces are generated with different curvatures and the entrance and exit surfaces are in the same line. A wave front under test is focused into the center of the beam splitter. The reflected light from the beam splitter is again focused onto the beam splitter after reflections from two spherical surfaces of the cube. Finally, the beam travels in the same direction as that of direct transmitted beam, but with a change in numerical aperture. Consequently, two wave fronts are radially sheared to produce an interference pattern. The interferometer is compact and simple to make. Its alignment is easy because the incident test wave front is in line with the sheared wave fronts. Aberrations are introduced into the interferometer by the spherical nature of the curved surfaces, and aberration analysis is also presented. Some applications of the interferometer for testing lenses and assessing the quality of emerging wave fronts from the exit-slit of a monochromator are also suggested.

© 1990 Optical Society of America