Abstract: Disclosed is a magnetic reading head using the Hall effect. In this head, the active element comprises a substrate on which the following are epitaxially grown: a layer of a semiconductor material with high electron mobility and a magnetic metallic multilayer formed by stacked layers of magnetic materials and non-magnetic materials, the layer of semiconductor material and the multilayer being electrically insulated from each other. This head also has electrodes for current supply and Hall voltage detection that are in contact with the layer of semiconductor material. The disclosed device can be applied to the reading of magnetic recording media.

Abstract: An automatic defect correction drive utilizing feedback in an image display device. According to the present invention, during an acquisition phase, a test image constituted of bright points of known positions distributed on a screen is displayed. This displayed image is then analyzed via an image acquisition device, to deduce from it the scanning, focusing and amplitude corrections to be applied to the display, so that the test pixels displayed on the screen have their expected positions and characteristics. These corrections are then interpolated for the intermediate pixels between test points, and then, during a continuation phase, these corrections are updated.

Abstract: A device for the prevention of drowning accidents based on the principle of underwater acoustic transmission consists in equipping an acoustic transmitter which communicates with at least one hydrophone placed at the bottom of the water, the hyrophone being connected to an alarm or to adapted rescue means.

Abstract: System for detecting free particles in component housings assembled on a printed-circuit card, according to which the card is made integral with a vibrating frame by a pneumatic mechanism. A removable piezo-acoustic sensor makes it possible to test for the presence of free particles in one or more of the component housings.

Abstract: Disclosed is a method for the fabrication of field emission peaks using a monocrystalline substrate with a suitable orientation coated with an insulating layer where square-shaped elementary zones with a suitable orientation with respect to the substrate have been removed. Silicon is deposited by selective epitaxy in these zones. The epitaxial growth of silicon, at high speed parallel to the substrate and at low speed along faces of the substrate at 45.degree. to the substrate, enables the making of pyramidal peaks which, afater being coated with tungsten, form emitting peaks.

Abstract: In a device for the suspension of a sonar acoustic base within its protection dome, two connection rods are used. These two connection rods are hinged, by one side, on the hull of the ship and, on the other side, on the acoustic base. These connection rods form a triangular system which, during the motions of the base, dictates a rotation of this base about an instantaneous center of rotation R located above the center of gravity G of the base. In this way, when the base touches the internal surface of the dome, the impact occurs as a surface-to-surface impact and not as a corner-to-surface impact. This limits the damage caused by the impacts, thus making it possible to obtain, simultaneously, a very free suspension of the acoustic base and efficient protection of the sonar dome.

Abstract: The disclosed network comprises standard sensors and intrinsic sensors with optic fibers. It is optically supplied. It has a circuit for addressing the channels of sensors with active couplers, also optically supplied. Each standard sensor is associated with an integrated optic element. The outputs of the sensors are all coupled to an optic fiber return bus.

Abstract: The self-retracting sighting device for an onboard optoelectronic localization and identification system has an elongated shape such that its rotation axis in elevation, beneath the fuselage of the carrier, is off-centered with respect to the input pupil. For the bottom line of sight, the device protrudes out of the fuselage to a major extent but, when the elevation angle increases, the device self-retracts beneath the fuselage, the top lines of sight being obtained without hindrance to the pilot's visibility. By additional rotation about the elevation axis, the input pupil is completely retracted beneath the fuselage, that part of the sighting device that protrudes out of the fuselage being then at its minimum and having an aerodynamic shape. The device can be applied notably to carriers in which the pilot's visibility is essential, for example during the stages of touchdown on aircraft carriers.

Abstract: The disclosed static reading head includes a dense network of micro-heads. Each of these micro-heads has a magnetic circuit body made of ferrite, closed by the tape to be read through narrow Permalloy pieces. The micro-heads are associated with lines of excitation wires supplied with DC current with a high-frequency component, and columns of reading wires connected to detection circuits.

Abstract: A tunable laser source comprising a laser source emitting a pump beam towards a Raman cell. It transmits a beam at a Stokes wavelength to a non-linear crystal. Depending on the angle of this beam with the optical axis of the crystal, the non-linear crystal transmits two output waves at wavelengths that are different from the Stokes wavelength.

Abstract: An infrared detector based on pyroelectric material, of the type associated with a reading circuit prepared on a semiconductor substrate, the substrate also supporting conductive blocks designed to transmit the electrical signals generated by the pyroelectric material towards the reading circuit. Each conductive block corresponds to a picture element or pixel, wherein the detector is formed by a layer of pyroelectric material deposited on that side of the semiconductor layer having the conductive blocks. The pyroelectric material has a thermal conductivity of K<1 W/m..degree.K., a counter-electrode covering the layer of pyroelectric material on the side opposite the conductive blocks.

Abstract: A method for making a microcavity in an enamel layer is disclosed. For this purpose, a layer of a carbon-based material with the dimensions of the microcavity to be obtained is provided. This layer is coated with an enamel except in a limited zone. The unit is heated to high temperature so as to cause combustion of the carbon-based material. The combustion gases escape through the reduced zone.

Abstract: The magnetic head has poles at each intersection of the matrix of wires. These poles connect the pads of the same column of pads, a gap being defined between the pads of the same intersection of wires and being parallel to the data wire.

Abstract: The field of the invention is that of power lasers pumped by coherent optical sources, such as laser diodes. The aim of the invention is to provide a structure of illumination of a laser rod enabling both efficient removal of the calories released by the coherent optical pumping sources and high homogeneity of the rod pumping operations. The structure is characterized in that the optical sources of at least one set of optical sources are arranged on one and the same delocalized support and in that said structure comprises reflecting means for the transmission, towards the rod, of the illumination beam from said set of delocalized optical sources.

Abstract: Disclosed is a plasma panel wherein the row electrodes and/or column electrodes are arranged to enable, notably, a selective type of addressing of several rows of pixels simultaneously. This is obtained, firstly, by a demultiplication of the row electrodes and by an increase in the number of column electrodes, the result thereof being a greater number of crossings between column and row electrodes and, secondly, by an increase in the surface of the crossings designed to form pixels, and by a limiting of the voltages applied to the electrodes.

Abstract: A capacitive detector of electromagnetic waves, comprises three electron levels, wherein an internal barrier prevents a strong coupling between two levels of two neighboring wells. During an irradiation, the electrons are excited from a first level to a second level. The electrons then relax towards a third level until they relax, by tunnel effect, towards the first level. During the transition from the first level towards the third level, a dipole is created. This dipole can be detected by a detector, through the measurement of a potential difference at the terminals of the device.

Abstract: The disclosed device can be used to determine coordinates expressing the angular deviation between the direction in which a missile is located and a line of sight in which a target is located. The device comprises means to project and shift an image on a linear senor, in such a way that the field of acquisition of the homing device has a section, by a plane perpendicular to the line of sight, that is ring-shaped having a diameter corresponding to a wide field aperture at the moment when the missile is launched, so that the missile is definitely intercepted in the field of acquisition, and then having a diameter that is variable as a function of time in such a way that the ring follows the missile as and when it approaches the line of sight through the action of a remote control system or a directive beam system.

Abstract: The quantum well semiconductor laser has at least one ultrafine layer with a thickness smaller than the critical thickness, the material of which is isoelectronic with that of the well.

Abstract: This Doppler radar for the detection and localization of helicopters through blade flashes works in a band located between 300 MHz and 20 GHz and identifies the blade flashes by the width of their frequency spectrum and their duration. It uses, at reception, a multilobe antenna associated with several parallel signal processing chains specialized in the detection of helicopters, enabling detection over a widened zone as well as precise localization. Each chain has a phase amplitude detector PAD (10, 10') followed by a Doppler filter MTI (20, 20') selecting the wide frequency spectrum, a module computing circuit (30, 30'), a contrast circuit (40, 40') eliminating excessively long echoes, a threshold circuit (50, 50') and a false alarm reduction circuit FAR (60, 60') eliminating excessively short echoes. The chains lead to a relative bearing computation circuit (100) performing angle measurements when this is possible.

Abstract: Disclosed is a device designed to selectively absorb the electromagnetic waves coming from multiple reflections in a microwave lens. In an antenna of the type including an energy source and a lens, where the lens is formed by a plurality of parallel channels separated by conductive planes, the device has a slot made in each of the conductive planes, arranged on the input face side of the lens, and also has localized or distributed resistors connecting the two edges of the slot. The geometry of the entire unit, and the values of the resistors are such that the waves coming from multiple reflections are absorbed by the resistors.