Tilted-reference-beam lateral shearing interferometer utilizing carrier-frequency photography.

Double-exposure carrier-frequency photography where the grating is rotated between exposures is used for observing phase objects. The resulting interferogram is similar to those obtained from interferometers using a tilted reference beam. Positive and negative gradients of the phase variation can be distinguished. Furthermore, it is shown that the image of a grating in carrier-frequency photography can be achieved by using an image-forming lens or by using the self-imaging property of the grating.