Holographic device
US4582389A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 18, 1982 |
| Grant date | Apr 15, 1986 |
| Priority date | — |
| Expiry date | Feb 18, 2002 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S359/90
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
There is disclosed herein a holographic optical element (HOE) which is particularly useful for head up display (HUD) systems and similar systems wherein the holographic element is used in a transmission mode as well as in a reflection mode. The element introduces little or no flare when bright light sources are viewed in transmission. The reduction in flare is accomplished by constructing the holographic element so that the fringe density (or spatial frequency) is low or zero at the surfaces of the hologram which forms the holographic element, or stated differently, the fringes in the hologram are formed parallel or substantially parallel to the surfaces of the hologram so that no fringes or very few fringes intersect the surfaces of the hologram. This is accomplished through control of the construction geometry to appropriately orientate the fringes, and a suitable fringe density is approximately two or fewer line pairs per millimeter for a typical application. The exposure rays from a point source used in constructing the hologram are, for example, perpendicular or substantially perpendicular to the surfaces of the gelatin or other sensitive material from which the hologram is ma…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.