Diffractive optical elements (DOEs) are optical components that deflect light into multiple orders at precise angles. Periodicity and their spatial frequencies, rather than the surface topography profile, determine the optical performance., different diffraction angles) known as diffracted orders. The perhaps simplest example are diffraction gratings and similar devices where. Conventional reflective and refractive optics, also known as geometric optics, describe light as a ray that can be reflected, refracted, diffused, or absorbed by optical materials (like polished glass, colored frosted plastic, human skin, matte white paint, etc. Thanks to their high level of functionality, several optical functions can be integrated simultaneously in a single element.