The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 15, 1986
Filed:
Feb. 18, 1982
Robert B Wood, Hillsboro, OR (US);
Robert F Cannata, Torrance, CA (US);
Flight Dynamics, Inc., Hillsboro, OR (US);
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 made, or variations in the angle of incidence of the exposure rays are otherwise minimized.