Abstract: An image forming a sighting reticle can be displayed at infinity in the landscape under observation without any need for a collimating optical system. To this end, a birefringent crystal plate having parallel faces is placed between two crystal plates employed as polarizing filters and consisting respectively of a polarizer and an analyzer in order to produce the reticle in the form of interference fringes centered on the line of sight. The very lightweight sighting device can be integrated in one eye-glass of a spectacle frame or in a helmet visor. Complementary diodes can be incorporated in the device for providing information relating to directional prepositioning and the like.

Abstract: A cartographic indicator, usable aboard an aircraft, comprises an analyzer continuously scanning a recording medium such as an optical film or a magnetic tape on which sections of a multicolor map are stored with a reduced spectral range, i.e. as a limited number of intensities possibly allocated to two different color components. The signals or pairs of signals emitted by the analyzer upon point-by-point scanning of the recording medium are fed to a transcoder, including a programmable read-only memory, which converts them into respective combinations of three signal components respectively representing the basic colors red, green and blue; the relative magnitudes of these signal components determine the contributions of the corresponding basic colors to an image point visualized by a multicolor display device.

Abstract: A cartographic indicator, usable aboard an aircraft, comprises an analyzer continuously scanning a map representing the overflown terrain in a limited number of colors whose primary components red, green and blue are quantized as to their levels of intensity. In response thereto, a first PROM emits a multibit word identifying each scanned map point in regard to chrominance and luminance, this word being fed to a second PROM where some of its color components may be selectively suppressed by a command from an operator-controlled instruction generator. The resulting word read out from the second PROM is supplied to a third PROM connected to three decoders emitting corresponding control signals to a color CRT for visual display of a replica of the scanned map portions, not necessarily in its original colors. Synthetic video symbols may be superimposed on the displayed map replica with the aid of a mixer which may also be switched to replace the map representation by a radar image.

Abstract: An indicator system satisfies multiple flight-mission requirements by providing an aircraft pilot with a visual display consisting of a movable map and navigational data. The map is stored in video form in a high-capacity compact mass memory consisting of a video disk. The system further comprises a symbol and character generator as well as an intermediate memory which has a capacity larger than required for the map-zone image to be displayed together with navigation symbols on a television monitor. The unit is controlled by a microprocessor on the basis of data relating to latitude, longitude and heading of the aircraft in order to refresh the intermediate memory and to obtain an image displayed with a "top-north" or "top-heading" orientation.

Abstract: A radiation sensor for determining the angular location of a light source and locating a direction defined by a plurality of sources fastened to a movable structure such as a helmet-mounted sight visor. The sensor comprises a housing with an optical mask which is provided with transparent zones of circular shape, with the result that the omnidirectional radiation transmitted by a point source is confined within a cone. Radiation-detecting means constituted by linear arrays of photosensitive elements are disposed in a plane parallel to the mask so that the center of the projected circle corresponding to the angular direction of the source is determined by the positions of sensitized elements of the detecting strips.

Abstract: A radiation sensor improved to increase the signal-to-noise ratio in the presence of a luminous background of high light intensity and to reduce the danger of direct detection of solar radiation. The sensor comprises optoelectric shutter means associated with the transparent slits of the optical mask in order to pass substantially only the radiation emitted by the source to be located and received by the associated detector. The shutter can be provided from a plate of ferroelectric ceramic material so arranged as to form juxtaposed elements controlled selectively by a circuit as a function of the positioning of the source in the form of data processed by an ancillary computer.

Abstract: A coupler for interconnecting transmission lines in an optical communication system. In a preferred embodiment it comprises an elongated bi-conically shaped rod of transparent material which continues into two cylindrical mixing rods. The lines are split up into two groups coupled to respective ones of the two plane endfaces of the coupler. The dimensions of each tapered central portion are determined such that the radiation pattern in the common plane of the identical minor bases is substantially hemispherical no matter what the direction of propagation of the light modes along the axis from one end to the other, given the numerical aperture of the associated transmission lines.