Influence of unparallel grating planes in Talbot interferometry with crossgratings of different spatial frequencies in two directions

The effects of an arbitrary small inclination between two cross gratings on the moire fringes in Talbot interferometry are discussed when the frequenc ies of the grating differ in two perpendicular directions. We show that the small angles, alpha and beta, by which the beam-splitter cross grating is rotated around the two axes parallel to the two perpendicular line directio ns of the cross grating, have a greater influence on the moire fringes with cross gratings than that with one-dimensional gratings. A simple and pract ical detection method for the angles between the two unparallel grating pla nes in Talbot interferometry is also proposed. The theoretical analyses are proved by experimental results. (C) 2000 Optical Society of America OCIS c odes: 120.1880, 120.3180, 120.4120.