Effect of nonuniform pit structure on self-imaging of periodical gratings.

Self-imaging possibilities for periodical gratings that have nonuniform pit structure are theoretically investigated. The diffraction of periodic arrays in the deep Fresnel region is analyzed according to the scalar diffraction theory. The expressions of the diffraction intensities of three different gratings that have binary square, binary circle, and Gaussian pit structure are considered. Talbot images of gratings with nonuniform pit structure are predicted to appear at multiple certain distances. The present paper shows that even a structure in short-range disorder may take on the self-imaging effect in a Fresnel field.