Control of quality of composite diffraction elements providing a possibility of visualization of defects of individual components

A possibility of distinguishing information on defects of a substrate and of a periodical microstructure upon their visualization for a composite diffraction element is substantiated. It has been shown for the first time that, for such a diffraction element, it is possible to distinguish separately reflections from macroscopic defects of the substrate and from the diffraction microstructure itself in the interference patterns, using a two-beam interferometer complemented by an optical system of spatial filtration.