초록 ▼

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

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.

대표청구항 ▼

An optical display system, comprising: projecting means for projecting images of information to be viewed by an observer; combiner means for reflecting the images to the observer, the combiner means being disposed to allow the observer to view a scene through it and including a holographic optical e

An optical display system, comprising: projecting means for projecting images of information to be viewed by an observer; combiner means for reflecting the images to the observer, the combiner means being disposed to allow the observer to view a scene through it and including a holographic optical element that is sandwiched between first and second transparent substrates and is positioned such that the second substrate is nearer to the observer, the holographic optical element having a curved shape and a surface fringe spatial frequency of approximately two or fewer line pairs per millimeter over its usable clear aperture for reducing flare from bright objects viewed through the combiner means; and means for mounting the projecting means and the combiner means in a predetermined spatial relationship so that the images which strike the holographic optical element pass through only one of the first and second substrates.