Method of fabricating diffraction grating using hyperbolic gratings and an apparatus for carrying out the method

摘要

A method of fabricating a diffraction grating comprises the steps of illuminating a first hyperbolic diffraction grating having a spatial frequency of f/2 with a spherical wave from a point light source to produce a diffracted ray, diffracting the diffracted ray from the first hyperbolic diffraction grating with second and third hyperbolic diffraction gratings having a spatial frequency of f, merging the diffracted rays from the first and second hyperbolic diffraction gratings on a photographic plate to record interference fringes. The point light source, the first, second and third diffraction gratings, and the photographic plate are disposed to satisfy the relationship <IMAGE> where d is the distance between the point light source and the first diffraction grating and c is the distance between the first diffraction grating and each of the second and third diffraction gratings and also the distance between each of the second and third diffraction gratings and the photographic plate. Also disclosed is an apparatus for carrying out the method.