Abstract: A display system suitable for large color television type images in which a thin membrane is charged electrostatically in a pattern corresponding to the image. The membrane is deformed locally by electrostatic force and the image is rendered visible by an optical arrangement in which the deformation varies the light transmitted through the display, the rear of which is illuminated.

Abstract: A helmet mounted projector provides offset and frame scanning capabilities or a dual channel computer generated image simulation system. The projector receives full color lasers from each channel via a separate optical path, including galvanometer controlled line scan offset mirrors designed to provide eye tracking capabilities, and combines said channels along a single optical axis to provide coordinated frame scanning from the complex image produced by the combined rasters.

Abstract: A field of view test apparatus utilizes a plurality of interchangeable acic masks to vary the resolution characteristics of a projected field of view. An eye or head tracker provides line of sight direction signals to a servo which positions the mask with the optical path of the projection to correlate the area of higher resolution with the direction of the line of sight.

Abstract: The invention provides line scanning and frame scanning apparatus for the projection of images, particularly for head-coupled area-of-interest visual display apparatus for ground-based flight simulators. The line scan apparatus is cockpit-mounted and comprises a modulated laser beam which is scanned over a line of fibre optic guides forming a ribbon by which the line image is transmitted to a helmet-mounted frame scanner. A sensor measures head/helmet movement to permit voluntary scanning of a wide angle of simulated view from the craft. The invention permits of lightweight helmet-mounted equipment for this purpose.

Abstract: The invention provides head-coupled area-of-interest visual display apparatus particularly for ground-based craft-flight simulators. The apparatus provides binocular, pseudo-collimated vision of a display, projected onto a part-spherical retro-reflective screen, for two pilots, covering an area of interest centered upon each pilot's line of view. A separate image generator is used for each pilot and may both be of the computer generated image, laser-scanned model or closed-circuit television type. For the pseudo-collimated viewing, the same image is projected for left and right eyes for each pilot from points on a respective pilot helmet, horizontally in line but vertically displaced above the pilot's eye position. Line scan apparatus is mounted in the pilots' cockpit; line image transmission is by fibre optic light guide ribbons; and frame scan apparatus is mounted on the two pilots' helmets.

Abstract: The invention provides head-coupled area-of-interest visual display apparatus particularly for ground-based craft-flight simulators. The apparatus provides binocular, three-dimensional vision of a display, projected onto a part-spherical retro-reflective screen, for one pilot, covering an area of interest centered upon the pilot's line of view. The image generator used may be of the computer generated image, laser-scanned model or closed-circuit television type. For the three-dimensional viewing, a modified image is provided for each eye and the two images are separately projected from points on a pilot's helmet horizontally in line but vertically displaced above the pilot's eye positions. Line scan apparatus is mounted in the pilot cockpit; line image transmission is by a pair of fibre optic light guide ribbons; and frame scan apparatus is mounted on the pilot's helmet. A position sensor detects head/helmet movements to permit voluntary scanning of a wide angle of simulated pilot view from the craft.

Abstract: The invention provides head-coupled area-of-interest visual display apparatus particularly for ground-based craft-flight simulators. The apparatus provides a display projected onto the inside of a part-spherical shell which surrounds the pilot and carries a retro-reflective screen. The displayed scene covers an area of interest dependent upon craft position and heading and viewer's instantaneous line of view. The image generator may be of the computer generated image, laser-scanned model or closed-circuit television type. Multiple images are required for stereoscopic viewing or for more than one viewer. Line scanning apparatus is cockpit-mounted; line image is transmitted by fibre optic light guide ribbon and frame scan apparatus is mounted on a helmet worn by the viewer. A sensor measures head/helmet movement to permit voluntary scanning of a wide angle simulated view from the craft. The projected image is divided into zones each zone using separate line-scanning means and fibre optic light guide.

Abstract: The invention provides head-coupled area-of-interest visual display apparatus particularly for ground-based craft-flight simulators. The apparatus provides binocular vision of a display projected onto the inside of a part-spherical shell which surrounds the pilot and carries a concave retro-reflective screen. The display covers an area of interest determined by craft position and attitude and the viewer's instantaneous line of view. The image or images are projected from points horizontally in line but vertically displaced above the viewer's eye positions. If the retro-reflective screen material has a very small angle cone of reflection, light is reflected back to the projection point rather than to the viewer's eyes. The invention provides a screen reflection characteristic modified in all vertical planes by the use of an optical grating in combination with a highly retro-reflective screen material.

Abstract: The invention provides head-coupled area-of-interest visual display apparatus particularly for ground-based craft-flight simulators. The apparatus provides binocular, pseudo-collimated vision of a display, projected onto the inside of a part-spherical shell which carries a concave retro-reflective screen and surrounds the pilot. The displayed scene covers an area of interest centered upon the pilot's line of view. The image generator used may be of the computer generated image, laser-scanned model or closed-circuit television type. For the pseudo-collimated display, the same image is projected for left and right eyes from points on a pilot's helmet above the pilot's eye positions. Line scan apparatus is mounted in the pilot cockpit. Line image transmission is by fibre-optic light guide ribbon and two such light guide ribbons are used to restrict impairment of the image by fibre fracture. Common frame scan apparatus is mounted on the pilot's helmet.

Abstract: The invention provides head-coupled area-of-interest visual display apparatus particularly for ground-based craft-flight simulators. The apparatus provides a stereoscopic pair of images for both a pilot and co-pilot, projected onto the inside of a part-spherical shell, which carries a concave retro-reflective screen and surrounds the two pilots. The display scenes cover an area of interest centered upon each pilot's line of view. A separate image generator is used for each pilot and may be of the computer generated image, laser-scanned model or closed-circuit television type. For stereoscopic viewing a modified image is provided for each eye of each pilot and for each pilot the two images are separately projected from points on a respective pilot helmet above the eye positions. Line scan apparatus is mounted in the pilots' cockpit; line image transmission is by two pairs of fibre optic light guide ribbons; and frame scan apparatus is mounted on the two pilots' helmets.

Abstract: A laser system designed to minimize mode beating by splitting an incident laser beam into two approximately equal components, transmitting the components along separate paths of unequal lengths and recombining the components at a beam combiner to form the emergent laser beam. Laser mode beating is effected at frequencies dependent upon the interferometric path difference. Mode beating elimination at further frequencies is possible using further splitter/combiner combinations in series. A three-color laser modulator uses two different laser sources, each with splitter/combiner mode beating suppression optics. One beam is further split to provide, in all, three paths through three color modulators, the three paths being combined at a dichroic combiner. A color laser projection display system includes conventional line and frame scanning means following the dichroic combiner of the three-color modulator.