Abstract: The phase comparator device with wide dynamic range comprises a phase comparator with reduced dynamic range to carry out the measurement, on a limited phase range, of the phase difference existing between an incident signal and an external reference signal modulated by a controlled phase signal generator. The device comprises, firstly, a phase accumulation circuit coupled to the output of the phase comparator for the successive accumulation, at determined instants, of the phase differences measured by the phase comparator and actuate the controlled phase signal generator so that its phase permanently follows the value of the phase differences cumulated in the accumulation circuit and, secondly, an adder circuit coupled to the output of the phase accumulation circuit and to the output of the comparator to add the phase difference measured by the phase comparator to the contents of the accumulation circuit. Application: phased carrier tracking loop for satellite navigation receiver.

Abstract: The present invention concerns an arrangement for reading an optically readable carrier with diffractive tracks having a longitudinal axis and contours parallel to the axes. Along each of the contours, the reference surface deviates towards zones which are not coplanar with the reference surface. The tracks are diffractive all along the longitudinal contours in order to diffract a light spot when that light spot illuminates one of the tracks. The track is substantially the same width as the light spot. The contours are such that light emerging from the diffractive track has a spatial distribution which represents the amount of track misregistration between the spot and the axis of the track. The system of the present invention particularly involves a photoelectric detector arranged for collecting radiant energy emerging from the portion of the track which is illuminated by the spot and for detecting an amount and direction of track axis misregistration based upon the spatial distribution.

Abstract: The invention relates to a process for producing a plurality of magnetoresistive sensors on the same substrate. The invention particularly has as its object to facilitate a polishing phase of this process. The process of the invention comprises depositing a layer of a magnetoresistive material on a substrate, and then forming in this layer a plurality of magnetoresistive elements. The process further comprises making, at the site of each sensor and before the depositing the magnetoresistive layer, an inclined surface, in such a way that each magnetoresistive element is formed on this inclined surface and exhibits an edge directed outward from the substrate.

Abstract: An optical architecture enabling the intercorrelation of two instantaneous wideband temporal signals. The beam coming from a monomode laser is used to obtain two carriers (W1, W2) for signals R(t) and S(t) by the use of, for example, integrated optical modulators (mod1, mod2). These two carriers have orthogonal polarizations and are distributed in a 2D structure comprising spatial light modulators as well as polarization separator elements. P.times.P independent channels (Cl to Cn) are thus formed. Their detection on a matrix of photodetectors (modl to modn) makes it possible to obtain, on each of them, the intercorrelation signal for different delays of the signals R(t) and S(t).

Abstract: Disclosed is a novel method for obtaining conductive polymers enabling their conductive to be increased and thermally stabilized. The polymers are obtained by oxidative chemical process in the presence of a codopant, the anions of which are more stable than the oxidating anions. The synthesis of the polymer is furthermore followed by a thermal treatment operation by which the conductivity of the material obtained is stabilized. Application: microwave absorbents.

Abstract: An optical connection device includes at least one first rigid element fitted with an end which is preferably pointed; and at least one second element comprising a part made of elastic material such as silicon. Fasteners hold the end of the said first element against the elastic material of the said second element.

Abstract: The adherence of a wheel to a braking track is defined by a point of operation that is variable on an adherence curve as a function of the slip of the wheel. In operation, the braking torque servo control parameter utilized is the sign of the variation of the slope of the adherence curve at the above-mentioned point of operation. The braking torque is servo-controlled in such a way that this point of operation is the same as the point of maximum adherence of the adherence curve.

Abstract: This invention concerns a secondary radar antenna operating in S mode.The antenna comprises a row of columns (1) of radiating elements powered by a hyperfrequency distribution circuit (2) containing a summing channel (.SIGMA.), a difference channel (.DELTA.) and a secondary lobe suppression channel (.OMEGA.), each producing a radiation diagram. The antenna end columns (L, R) each produce at least one auxiliary radiation diagram offset with respect to the diagram produced by the summing channel and contributing with the other antenna columns (1) to the creation of the other three diagrams.Application: secondary radars in S modes in communication with a large number of aircraft per antenna revolution.

Abstract: Disclosed is an image projector of the type in which an LCD matrix screen is illuminated by two polarized beams after 90.degree. rotation of the direction of polarization of one of these two beams. Each of the two polarized beams is reflected at least once towards an optical axis on which the matrix screen is centered and at least once again towards the matrix screen. Furthermore, the image projector has means to make each beam polarized, so that each polarized beam forms an image of the light source before illuminating the matrix screen. The two polarized beams may thus be oriented towards the matrix screen in forming a small angle with one another, thus enabling the use of a projection objective with a small aperture.

Abstract: The disclosure relates to fluorinated chiral liquid crystals that incorporate a cyclohexyl grouping in their structure. They can be used as dopants and lead to mixtures of ferroelectric liquid crystals that have an application in display systems. They meet the following chemical formula. ##STR1## with 1.ltoreq.n.ltoreq.14 if X=CH.sub.2 Y=--CH.sub.2 -- with R=CmH.sub.2m+1 and 5.ltoreq.m.ltoreq.

Abstract: A non-linear optical fiber receives two light waves by its two ends, each light wave being modulated by means of two modulators. These light waves create photoinduced index variations in the fiber which are proportional to the intensity of the optical field. A reading source emits a reading wave in the fiber. This reading wave is reflected at least partially by the index variation or variations. A detector receives the reflected wave and makes it possible, through the computation of the returning time of the wave, to determine the position of the index variations. Applications: very wide passband signal correlators.

Abstract: An input screen scintillator for an X-ray image intensifier tube. The tube includes light conductive cesium iodide needles formed on an electrically conductive substrate. Each needle is entirely coated with a material such as a metal or a semiconductor which reflects the light travelling within the needle toward the inside of the needle. This coating can enhance the efficiency and resolution of the image intensifier tube.

Abstract: An imaging system is provided with integrated measurement of wear in at least one of the system's optical elements working in the transmission mode, in a given spectral band. The system includes a combination of optical elements and an imaging detector on which there is projected the image of an observed scene by means of the optical elements which produces a video signal of the observed scene. An alarm is provided to signal the existence of an optical element having a degree of wear which exceeds a critical value.

Abstract: A method for decomposing each field of movement of an image according to a coding tree and for identifying by a menu each movement vector present in the image by accompanying each vector by its codeword.

Abstract: The invention pertains to the field of fabrication, by vapor phase deposition, of the thin layers of monocrystalline, polycrystalline or amorphous material on a substrate having an identical or different nature. The aim is to provide a method, enabling this structure to be made, that includes a modulation of both the composition and the doping, in a direction that is not perpendicular to the surface of the substrate, notably in a lateral way to obtain a planar technology. According to the invention, this thin layer is made by conformal epitaxy, using a crystalline seed in gas phase, between two confinement layers made of a distinct material in such a way that there can be neither nucleation nor deposition of semiconductive material on the surfaces of said confinement layers and wherein the variation of the gaseous mixture of said gas phase is controlled to obtain said modulation of the composition and/or of the doping of said thin film.

Abstract: A vibration testing platform includes, on one side, a fastening point connected to three actuators placed in orthogonal directions to one another by link-rods hinged at both ends thereof and, on the other side, three fastening points, each point being connected to the ground by a link-rod hinged at both ends thereof. The two end link-rods are vertically oriented and the third one is horizontally oriented and placed in a transversal direction.

Abstract: A collision-avoidance method for cooperating carriers consists of:transmitting, from each carrier, monochromatic pulsed light waves, coming from at least two wide-field optical transmission devices to cover the space around the carrier and thus define a zone of proximity, the power of the optical transmission defining, under given weather conditions, the range of the transmission and hence the zone covered;and receiving, at each carrier, the monochromatic, pulsed light waves radiated into space by other cooperating carriers, on at least two wide-field reception devices covering the space around the carrier. Each intrusion of a carrier into the proximity zone of another carrier prompts the detection of light radiation and the triggering of an alarm on either carrier. Applications are to air anti-collision systems.

Abstract: Disclosed is a frequency doubler having a quantum well semiconductor structure and a second-order non-linear susceptibility grating that can be used to amplify notably the frequency doubling. The grating can be recorded optically or electrically within the semiconductor structure and has a pitch in the plane of the structure. Such a frequency doubler finds particular application to optical recording or reading systems.

Abstract: Disclosed is a method for the adjusting of the detection threshold of a radar receiver for a distance zone called a search zone surrounded by distance zones called adjacent zones, fitted out with a module enabling the computation of the mean value as a function of the distance of the ambient noise along an axis starting from the receiver wherein, for each search distance zone, the detection threshold is raised by a zero value when the ambient noise is low and by a value that increases monotonically with the level of the noise measured when the ambient noise is greater than a pre-determined threshold.

Abstract: The strip is designed to optically interconnect a set of printed circuit boards mounted in a housing. It comprises:a U-section (29) lying alongside and against the edge of the set of printed circuit boards with its back (30) turned towards the printed circuit boards and including two lateral flanges, the back containing apertures (39, . . . , 44) drilled at the same pitch as the spacing of the printed circuit boards andoptical fibers (37, 38) laid in the section (29), running from one aperture (39, . . . , 44) to another, each aperture (39, . . . , 44) drilled in the back (30) of the said section (29) and containing one or several optical fiber (37, 38) ends lying opposite an optical half-connector mounted on the edge of one of the printed circuit boards.