A diffractive optical element is an optical device that utilizes interference and diffraction rather than refraction or reflection, to shape an emerging wavefront. In this talk we will concentrate on the image-forming capabilities of diffractive optics.
G. Michael Morris, G. Michael Morris,
"Diffractive optics: from basic research to practical applications", Proc. SPIE 3482, International Optical Design Conference 1998, (21 September 1998); doi: 10.1117/12.322061; https://doi.org/10.1117/12.322061