ABSTRACT
In general, the term "diffractive element" (DE) covers the range of elements that use the wave nature of light to control light by means of diffraction. The properties of diffractive optics that are shared with conventional elements do not depend on the specific type of diffractive element. Diffractive optical elements introduce a controlled phase delay into an optical wavefront by changing the optical path length, either by varying the surface height, or by modulating the refractive index as a function of position. The theoretical basis for modeling diffractive optics can be divided into three regimes: geometrical optics, scalar, and vector diffraction. DEs operate at the wavelength for which they were designed. The unique properties of the DE can be used to correct the aberration of the optical systems that consists of conventional optical elements and DEs by combining this with refractive elements to produce achromatic diffractive/refractive hybrid lenses for use in optical systems.
