Lens-based theory of the Lau effect

A new theoretical model of the Lau effect is presented. The transmittance of a diffraction grating can be expressed in an equivalent form as the sum of transmittances of thin cylindrical lenses. Therefore it is possible to explain the Lau effect on the basis of the well-known imaging properties of lenses. According to the given approach, the Lau fringes are created by overlapped images of the first grating that are formed by a set of lenses corresponding to the second grating in the setup. The theory leads to an exhaustive description of the Lau-effect parameters. In particular, one can indicate the shape of the Lau fringes and localize planes of the fringes dependent on the axial distance between gratings and their periods. © 2000 Optical Society of America.