Variable surface relief kinoform optical element
US5969864A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 25, 1997 |
| Grant date | Oct 19, 1999 |
| Priority date | — |
| Expiry date | Sep 25, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/1876
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A kinoform optical element (KOE) has different surface relief heights in different zones of the kinoform surface, in order to optimize the first order diffraction efficiency in each zone. By increasing the first order diffraction efficiency, noise as well as ghost image problems may be reduced and contrast and resolution may be enhanced. In an exemplary embodiment, each zone, or even different areas of the same zone, has a non-constant step height that is preferably defined by a predetermined relationship between an optimal step height and an associated predominant angle of incidence associated with that particular zone or area. In the case of an optical system having a relatively large aperture and a relatively narrow field of view, each point of the KOE sees the entire image; the associated predominant angle of incidence at that point may be defined by a so-called "marginal" ray from the center of the entire image space (i.e., on the optical axis and at the effective "middle" of the usable depth of field). In the case of an optical system having a relatively small aperture and a relatively wide field of view , each point of the KOE sees only a portion of the image; the associated…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.