SELF-IMAGING OF THREE-DIMENSIONAL PHASE GRATINGS

We present a general solution of the wave equation, obtained by the four-dimensional spectral method, for diffraction of a plane monochromatic light wave by a three-dimensional (3D) phase grating layer of finite thickness. As an example, we consider spherical particles in 3D phase gratings with orthogonal and hexagonal geometry. Conditions for the strong self-imaging of a 3D grating layer and for the weak self-imaging of a two-dimensional (2D) grating are formulated and investigated. Intensity distributions for diffracted light in planes of positive and negative self-imaging and in a plane of lowest contrast are computed and compared for 2D and 3D gratings. Some aspects of the Talbot and Lau effects for 2D and 3D phase gratings are discussed.