Abstract: An optical display system (10) presents visual source information to an observer (18) The display system includes a vision unit (14) that has reflective surfaces (16) through which the observer can view an outside world scene and which reflect source information emanating from an information source (22) for display to the observer In a preferred embodiment, the optical display system constitutes a head-up display system for an automobile and the observer is the driver of the automobile. The vision unit constitutes an automobile windshield with or without a reflection enhancement material and whose inner and outer surfaces reflect source information carried by light propagating form the information source, such as a liquid crystal display (32). A projection lens system (24) positioned between the inner surface of the windshield and the information source has optical light-directing properties for compensating for optical aberrations introduced by the nonplanar windshield surface.

Abstract: A method for processing exposed holograms to enhance their thermal stability and enable them to withstand a windshield lamination process is disclosed. The secondary processing procedure entails an optional step of applying a moisture barrier to the hologram, followed by heat stabilizing the hologram and storing it in a relatively low humidity environment. Specifically, the exposed holographic material is heated to a peak temperature of about 135.degree. C. and thereafter cooled to provide a thermally stabilized holographic material that maintains its holographic qualities over a relatively broad range of temperatures.

Abstract: An arrangement for head-up display system components incorporated into an aircraft cockpit forward of the ejection plane (124) provides space for accommodating a head-down display device (132) immediately beneath the over-nose vision surface (128) and adjacent to the ejection plane (124). The arrangement of components minimizes the amount of angular change in the pilot's line of sight that is required when the pilot moves his head to change his view from the outside real world scene to the head-down display device.

Abstract: An optical display system (10) presents visual source information to an observer (18). The display system includes a vision unit (14) that has reflective surfaces (16) through which the observer can view an outside world scene and which reflect source information emanating from an information source (22) for display to the observer. In a preferred embodiment, the optical display system constitutes a head-up display system for an automobile and the observer is the driver of the automobile. The vision unit constitutes an automobile windshield with or without a reflection enhancement material and whose inner and outer surfaces reflect source information carried by light propagating from the information source, such as a liquid crystal display (32). A projection lens system (24) positioned between the inner surface of the windshield and the information source has optical light-directing properties for compensating for optical aberrations introduced by the nonplanar windshield surface.

Abstract: A method of constructing flare-free reflection holograms uses a light scattering mechanism positioned between a first exposure beam and holographic recording material to remove the spatial coherence from all but adjacent rays within a relatively small angular range before the light rays of the first exposure beam strike the hologram surface. A second exposure beam of spatially coherent light rays interferes with mutually spatially coherent light rays of the first exposure beam to form a primary hologram. Light rays reflected off the holographic recording material noncontacting surface of the substrate interfere with the light rays of the first exposure beam but do not form parasitic hologram recordings because the interfering light rays are not mutually spatially coherent.

Abstract: The present invention comprises a system for detecting windshear and associated downdraft effects when they are encountered in flight by an aircraft. The system includes an input unit (12), a first processing unit (14), a second processing unit (16), an output unit (18), and a pilot warning device (20). The input unit receives aircraft performance data from the instruments and/or flight systems on the aircraft and preconditions this data to produce a set of signals corresponding to various aerodynamic and inertial input parameters. The first processing unit differences signals representing the aerodynamically derived and inertially derived accelerations of the aircraft in order to generate windshear signals. These windshear signals are then corrected for pitch rate induced coriolis acceleration effects. The corrected signals are used to form a signals representing longitudinal windshear along the horizontal heading axis of the aircraft and the change in aircraft climb gradient due to longitudinal windshear.

Abstract: A holographic windshield (10) includes an inner glass ply (36) having an inner flexible optically transparent inner interlayer (42) overlaid upon its inner surface (40). A middle flexible transparent interlayer (44) is overlaid upon the inner interlayer. The middle interlayer has an opening (46) formed therein. A flexible hologram (12) is fitted within the opening in the middle interlayer. An outer interlayer (48) is overlaid upon the middle interlayer including the flexible hologram. An outer glass ply (50) is overlaid upon the outer interlayer. The two glass plies are bonded together to form a unitary article. Also disclosed is a method for processing a holographic combiner to withstand a windshield construction process employing lamination techniques.

Abstract: The present invention constitutes a system for generating an elevator command signal for directing a pilot in guiding his aircraft along a path effective for recovering from hazardous windshear conditions. The system includes a descending mode guidance subsystem (10), an ascending mode guidance subsystem (12) and a switching mechanism (14) for shifting between the two subsystems. The descending mode subsystem includes an acceleration generator (20), a flight path command generator (22), a flight path error generator (24), a descending mode pitch error generator (26), an airspeed control device (28) and a descending mode signal controller (30). These components are connected serially together and operate to form an elevator command signal corresponding to the acceleration required to halt the descent of the aircraft by a fixed altitude level.

Abstract: A head up display system includes a combiner alignment detector (24) that determines whether the combiner (22) and a cathode-ray tube (CRT) (18) are aligned within a preassigned operational tolerance. The CRT emits display symbology that reflects off the combiner toward an observer. The combiner is secured to a combiner bracket (38) which is pivotally mounted to a mounting structure (70) having a stationary relationship with the CRT. A light emitting diode (LED) (86) and a light-sensitive linear position detector (88) are secured to the mounting structure. Light rays emanating from the LED are reflected by a mirror (34), which is secured to the combiner bracket, and strike the position detector. Pivotal motion of the combiner bracket relative to the mounting structure results in movement of the mirror relative to the LED and the position detector.

Abstract: A method of preventing a reduction in image contrast in a head-up display. The head-up display is comprised of a visual information source, a lens, a wavelength selective reflecting element, and a combiner which reflects at least some of the wavelengths from the information source which reflect off the reflecting element. The reflecting element, in addition to being wavelength selective, is provided with optical power to reduce aberrations which would otherwise result from operating the combiner at an off-axis angle.

Abstract: A head up display includes a simplified holographic combiner which has a low surface spatial frequency for avoiding flare. Symbology generated by a cathode-ray-tube is focused by relay optics and then reflected by a holographic optical element toward the holographic combiner. The last mentioned holographic optical element is provided with optical power in part compensating for distortions attributable to the large off-axis angle at which the holographic combiner is operated.

Abstract: An optical display system employs a holographic optical element that has a holographic fringe pattern which is coordinated with the phosphor emission peak of a cathode ray tube to eliminate perceptible variations in image brightness. The holographic optical element has a reflection characteristic that defines two diffraction efficiency peaks which are resolved by a low diffraction efficiency dip that is interposed between them. The optimum wavelength spacing between the two diffraction efficiency peaks for a given wavelength spacing is determined by computing for all observer head positions and look angles of concern the differences among the areas under the integrated efficiency characteristics for the reflection characteristic of the holographic optical element and the phosphor emission characteristic of the image-producing cathode ray tube. The optimum wavelength spacing is that which provides the desired variation among the computed difference values, which respresent the display brightness uniformity.

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.