Technique to eliminate scattered light in diffractive optical elements

• Main Authors: MEYERS; MARK M, ALBRECHT; RICHARD E
• Format: Patent
• Language: English
• Published: 01.09.1998
• Edition: 6
• Subjects: OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICS; PHYSICS

Diffractive optics using surface relief profiles, also known as blazed gratings having ramps and edges or steps (also referred to as blazed facets with discontinuities at the interfaces between adjacent facets) defining grating lines and phase delays to which light propagating through the grating are subject. Diffractive lenses which are known as phased Fresnel zone plate lenses or kinoforms, also have annular blazed facets with discontinuities, steps at the interface between adjacent facets at the steps which facets define the zones of the lens. These steps are either aligned parallel to the light incident on the grating or coated with an optically opaque material, thereby preventing the transmission of incident light which is not diffracted, but would be scattered or transmitted at the steps. The contrast and quality of an image provided by the diffractive lens at a plane spaced from the grating, which may be the focal plane of the diffractive lens, is therefore enhanced.