Abstract

A holographic plate doubly exposed to the two-beam interference pattern with a rotation between two exposures can be processed to direct considerable light in four desired directions. This plate serves as the beam splitter in the interferometer. With four line gratings in the other plane to redirect the light and produce an interference pattern, an elliptical (or circular) dotted array with unity contrast can be produced with white-light extended-source illumination.¹ However, this interferometer cannot produce a dotted structure with continuously variable fringe periods in orthogonal directions. When the first grating is replaced by two line gratings, with their line structures inclined at an angle (almost in contact), one of these line gratings combined with two line gratings from the other plane, would constitute a line-grating interferometer. The conditions under which a dotted interference pattern with unity contrast can be produced are discussed, together with some experimental results.

© 1990 Optical Society of America