Abstract: Device for creating optical delays in which several secondary optical paths are provided and placed in series and in shunt with a main optical path. Access to the secondary optical paths is obtained via switches that are placed along the main optical path. The length of the delay circuits are in a geometric progression whose common ratio has the value of two. Depending upon the switching states of the switches it is therefore possible to obtain a series of equal distant delays with a relatively small number of switches.

Abstract: Disclosed is a device for supply to the radiating elements of an array antenna with electronic scanning, notably applicable to an MLS type landing system. The disclosed antenna has as many (n) phase-shifters as it has radiating elements each of the phase-shifters being connected to a plurality (m) of neighboring radiating elements forming a sub-array. The sub-arrays are interleaved so that each of the radiating elements is supplied by means of m phase-shifters. As a result, an array antenna with very small minor lobes is obtained.

Abstract: Disclosed is an original method for preparing composite materials for a display screen, these materials containing a polymer, liquid crystal and dye. The present problem is one of inserting molecules of dye into composites of this type. The disclosed method proposes the preparation, in a first step, of a porous film of reticulate polymer. Then, molecules of liquid crystal (XL) and molecules of dye (C) are made to diffuse therein by a polymer-expanding solvent. After evaporation of the solvent, a film of polymer is obtained with inclusions containing liquid crystal (XL) and dye (C) with a wide range of concentrations in liquid crystal, thus making it possible to optimize the performance characteristics in terms of contrast and control voltage of the screen thus made.

Abstract: A device for the optical processing of electrical signals. An optical source (L) emits a multiple-wavelength optical beam (B1). A modulator (MOD) modulates this beam. An optical fiber (F) receives the modulated beam and delays the components corresponding to the different wavelengths differently. A dispersive grating disperses wavelengths contained in the modulated beam in different directions. A spatial light modulator controls the level of optical intensity of different directions of the dispersed beam. An optical detection system receives the beam processed by the spatial light modulator. Such a device may find particular application to a transverse filter and microwave signal correlator.

Abstract: The invention relates to towed sonars. It consists in compensating electronically for the movement of the antenna in order to suppress the Doppler shift of the fixed echoes. In order to do that in a towed linear antenna (203) comprising N sensors (205), M (M<N) successive sensors are selected which are switched electronically in order to make them travel synthetically over the antenna in the direction opposite to the movement of the latter at a speed equal to twice the forward speed of the antenna. In order not to have too large a number of physical sensors, the signals from the latter are interpolated in order to obtain synthetic sensors which are sufficient in number to reduce the increment of the movement of the synthetic sub-antenna in such a way as to suppress the parasitic lobes due to the incremental nature of this movement. It makes it possible to increase the sensitivity of sonars without increasing their power. FIG. 2.

Abstract: In order to improve the contrast of a synthetic image generator, the usually implemented operations of luminance compression are eliminated. Instead, a computation of true luminosity is made and the function of adaptation of the eye is included by computing the true output light energy. Then, the video components of the signal are sent to a display system and are standardized as a function of the light energy of the image displayed and the possible range of the image display. The method includes producing images with a luminance range substantially equal to the true luminance range of an eye and sending this signal to the display system. The signal is varied for different images at a time equal to the time an eye adjusts to different images. The apparatus includes a main channel being corrected by a computing circuit, having a peak luminance extraction circuit and a light energy computing circuit for generating a luminance correction signal.

Abstract: The present invention relates to a process and a system for determining the position and orientation of a mobile, and to applications thereof.In order to ascertain both the position and orientation of a mobile, the invention proposes an interrogation/response process whose particular feature is to supply, to a given interrogation, two responses which are distinguished on the one hand, by different modulating frequencies and, on the other hand, by the fact that they are transmitted according to two patterns which differ in aim relative to one another. It is then possible, simply by measuring the angular deviation of either one of the two responses, and simply by measuring the ratio of the amplitudes of the two responses received, to deduce on the one hand the angular position .phi. and on the other hand the orientation .theta. of the mobile.The applications in the automobile sector are numerous (anticollision, control of road traffic and of compliance with the highway code, automatic toll points, etc.).

Abstract: A radar antenna includes a reception part constituted by elementary antennas, each elementary antenna delivering a reception signal to a computer for the formation of simultaneous radar beams by computation, and a transmission and reception part constituted by at least one elementary antenna. The computer uses the signals received by the elementary antennas of the reception part to form a set of radar beams within a solid angle radar beam formed by the elementary antennas of the transmission and reception part. The radar antenna finds particular application in the field of designation and trajectography radar.

Abstract: This analog-digital coding circuit comprises, in parallel on an analog-digital converter, a crossover detector. This crossover detector operates on the input analog signal of the converter and, by means of a delay circuit, taking account of the conversion time of the converter, commands the recording of values in a digital register placed at output of the converter. A digital subtractor, placed at output of the coding circuit, makes a systematic deduction, from the digital values delivered by the converter, of that value which is memorized in the digital register and corresponds to the offset voltage of the converter.

Abstract: A method for making an optical amplifier according to which a stack of the following layers is made by epitaxy: a first optical guiding layer; a first chemical attack barrier layer; a second optical guiding layer; a second chemical attack barrier layer; an active layer; a confinement layer; and a contact layer. Then at least one amplifier element followed by an optical guide located beneath this amplifier element are etched in these layers. The method can be applied to the making of optoelectronic devices such as modulators, change-over switches, distributors, etc.

Abstract: In a waveguide (1) having slots (2, 3) perpendicular to the axis of the waveguide, cut out in a narrow wall of the waveguide, there are positioned, on each side of each slot, pairs of metal flat plates (21, 22; 31, 32) symmetrical with respect to the central axis of the slot. These flat plates modify the electrical field at the associated slot and make it possible to excite it, the value of the coupling being set by the adjusting of the size of the flat plates and of their position with respect to the corresponding radiating slot.

Abstract: A CCD shift register having a reading device, or charge/voltage conversion device, at one end. This reading device or charge/voltage conversion device includes a diode, a precharging transistor, and an amplifier with high input impedance. To improve the efficiency of the charge transfer and, more generally, the behavior of the register, especially at high frequencies, it is proposed to shape the final gate of the register, and the diode, in such a way that the width along which the gate is adjacent to the diode (i.e. the width along which the end of the channel is adjacent to the diode) is great while, at the same time, the diode surface area is kept small.

Abstract: The read head according to the invention comprises a matrix network of elementary heads whose magnetic circuit comprises a magneto-resistive element. The different elements are electrically connected in columns and traversed by a current. Head selection lines enable the active line of heads to be selected. The read signal is collected on each column.

Abstract: Disclosed is a method for the discriminating of obstacles by means of a radar, and its different applications to the measurement of a liquid in a tank or vessel, or again to the elimination of unwanted or parasitic echos coming notably from the ground, for radars mounted on vehicles or controlling vehicle traffic. To implement the method, the obstacle to be discriminated must have a substantially plane surface. The disclosed method then consists in successively transmitting substantially plane waves at slightly different angular frequencies .omega..sub.i, each wave being furthermore sent with two different polarizations p and p' chosen in such a way that these different coefficients of reflection on the obstacles according to the incidence of the waves give a criterion of discrimination. The processing at reception depends on the use (measurement of distance, elimination of parasitic echos etc.).

Abstract: A material based on a conductive polymer consisting of particles of conductive polymer (P.sub.0), each particle being wrapped in a shell of water-insoluble, cross-linked polymer (P.sub.1).

Abstract: A thermal detector with a monolithic structure comprises a layer of material sensitive to infrared radiation and an insulating layer constituted by a thermostable polymer that can be deposited as a thin layer and has a microporous structure. This insulating layer enables the thermal decoupling of the sensitive layer from the substrate comprising reading circuits with which the detector is provided. The performance characteristics of currently used monolithic infrared detectors can thus be substantially improved through the notable reduction of the thermal losses in the sensitive layer. This is achieved through the greatly reduced thermal conductivity of the layer of dielectric polymer. Application to infrared imaging devices.

Abstract: The disclosure relates to the servo-control of an electronic circuit that calls for the detection of the power delivered at its output. The disclosed device is essentially constituted by a field-effect transistor with zero bias V.sub.DS mounted between the ground and a matching network at output of the circuit. This transistor behaves either like a capacitor or like a diode. A low-pass filter, connected between the transistor and the network, delivers a detection voltage V.sub.det.

Abstract: An optical device, similar to binoculars, which includes, between the objective lens and the eyepiece a miniature screen displaying an image controlled by a computer, and an optical reflex device capable of superimposing the screen image on the image seen through the objective lens. The device also includes, selectively or cumulatively, a variable light attenuator and a light amplifier for night vision. The device can be used, in conjunction with a computer, to add further information on geographic positions, friends, enemies, infrared images, etc. into the scene seen through the binoculars.

Abstract: A diffusing display screen resulting from the combination of a cell comprising a polymer dispersed liquid crystal material which can be made diffusing, and of a cell comprising an electrochromic material which can be made absorbing and reflecting. Outside the operating mode, the display screen according to the invention has the advantage of being transparent, and thus capable of being fixed onto any surface (window, wall, etc.).

Abstract: An electrooptical modulation device formed on an electrooptical substrate, including a first region having a Y-junction for receiving an optical signal to be modulated and dividing the optical signal into two equal optical signals, a first modulation region of length L.sub.1 having two parallel optical waveguides spaced sufficiently apart to prevent optical coupling, a second section of length L.sub.2 over which the optical waveguides extend and define a coupling length l.sub.c2, this second section not being subjected to electrooptical modulation, a second modulation region of length L.sub.3 having two parallel optical waveguides, a third section of length L.sub.4 over which the optical waveguides extend and define a coupling length l.sub.c4, and a fourth section for separating the optical waveguides and delivering two modulated optical signals of different intensity. This device operates with reduced control voltages and makes it possible to enhance the linearity of the electrooptical response.