The Fraunhofer type requires the use of a Fresnel-
The Fraunhofer type requires the use of a Fresnel-Kirchoff integral. A grating of this type is used to split light into its various wavelengths, and consists of closely placed parallel slits. Patterns of it can be used to determine spacing between layers of atoms through an application of Bragg's law.   Using the de Broglie wavelength, occurrence of this for neutrons and electrons was one of the main arguments for quantum mechanics. The X-ray type of this was used to determine the shape of macromolecules like the alpha helix of proteins discovered by Linus Pauling and the double helix shape of DNA.  FTP, name this wave phenomenon exhibited by light as it curves around a thin opening, the subject of Young's double slit experiment.
The Fraunhofer type requires the use of a Fresnel-Kirchoff integral.
{Diffraction} (Prompt on {Crystallography} after {X ray})