Abstract: This optical filtering device includes a dichroic separator on the path of a light beam to be processed. According to the invention, it also includes a holographic filtering device situated in series with the separator on the path of the same beam. The holographic device can be oriented so as to adjust the angle of incidence of the beam and hence adjust its range of filtering wavelengths.

Abstract: An auto-test device for a radar includes at least one transducer located in the field of radiation of the radar microwave transmission, the transducer being configured to intersect a part of the radiated energy and to send it back to a receiver so as to create, in the receiver, a test signal modulated by beats of the transducer. The device further includes a synchronism mechanism configured to excite the transducer in synchronism with a sub-multiple of the frequency of sampling of a reception signal. The transducer is placed such that the receiver receives a test signal with a mean value close to zero.

Abstract: A charge/voltage conversion device of a CCD type charge transfer read register comprises a read diode and a read amplifier, wherein the read amplifier comprises a first amplification stage enabling the conversion, into current variations (.DELTA.I), of the voltage variations (.DELTA.Vg) collected at the terminals of the read diode and a second amplification stage enabling a reading to be made of said current variations. The disclosed device can be applied especially to photosensitive devices enabling the conversion of a light image into an electrical signal.

Abstract: The color display device includes at least a light source which emits at least two primary wavelengths and an array of holographic lenses (HL). Also included is a spatial light modulator (LCD) which includes one picture element (pixel) for each holographic lens with each pixel including one subpixel for each wavelength to be displayed. Each of the holographic lenses disperses the various wavelength and focuses each of them into one of the subpixels. The structure allows for a single lens structure for the various wavelengths.

Abstract: A UHF phase shifter including a UHF waveguide having an electrooptical element lying between two elements 3 and 4 made of materials which have permittivity higher than that of the electrooptical element. An electric polarization field is applied for controlling the electrooptical element and a UHF line is inserted into the element. The control of the orientation of the molecules of the electrooptical element allows for a variation of the index of the element as seen by the field of a UHF wave.

Abstract: A matrix type magnetic recording/reading head made in integrated fashion, including an electrically non-conductive ceramic substrate having a first main face and a second main face, each provided with connection areas. The two areas of the two faces are interconnected in sets of two by internal connection elements. A layer with high magnetic permeability is deposited on the first face of the substrate. The substrate bears a first series of row conductors and a second series of column conductors intersecting the row conductors, each conductor being connected to a connection area of the first face. Pairs of magnetic poles are located substantially at the intersection of the row conductor and column conductors, the poles of each pair separated by a gap space and being magnetically coupled to the layer with high magnetic permeability in two opposite zones defined by the intersection of a row conductor and a column conductor.

Abstract: The disclosure relates to differential input/output surface acoustic wave devices with proximity coupling. The disclosed device comprises a whole number N of acoustic channels, where N is at least equal to two. The acoustic channels are coupled together by proximity. A first acoustic channel comprises at least one transducer separated into several parts electrically connected in parallel with one another to form a first differential port (E+) and a second differential port (E-). The polarities of the different parts of the transducer are chosen so that the first differential port (E+) and the second differential port (E-) are electrically symmetrical. Application in particular to surface acoustic wave filters for portable telephones.

Abstract: Disclosed is a radar for the detection of obstacles. The radar uses at least four frequencies referenced F.sub.1, F.sub.2, F.sub.3, F.sub.4 such that:F.sub.1 -F.sub.3 =F.sub.2 -F.sub.4and such that:(F.sub.1 +F.sub.3)-(F.sub.2 +F.sub.4)=Cte where Cte represents a constant frequency value, the measurement of distance from the target being done on the basis of the difference in phase between two signals of which the first (r.sub.1 (t)-r.sub.3 (t)) is constituted by the difference between two received signals corresponding respectively to the frequencies F.sub.1 and F.sub.3 and the second (r.sub.2 (t)-r.sub.4 (t)) is constituted by the difference between two received signals corresponding respectively to the frequencies F.sub.2 and F.sub.4. Application in particular to automobile speed control.

Abstract: A recording/reading head for multitrack information media including magnetic tape recorders comprises a matrix of elementary heads positioned in rows and columns. The columns, and especially the neighboring columns, are not parallel to one another.

Abstract: A process for automatically controlling a hydraulic servovalve with a hydraulic slide valve displaced by a rotary actuator. The process includes a first loop for automatically controlling the delivery as a function of the measurement of the angular position of the rotary actuator and a second automatic control loop with variable control as a function of the pressure measurement. The first automatic control loop is a proportional action loop whose increase is constant for the absolute values of the pressure deviation which are less than at least a threshold value and then varies in an increasing manner for absolute values of the pressure deviation which are greater than the same threshold.

Abstract: A stage for the amplification of high frequency signals (HF) or intermediate frequency (IF) signals comprises a referenced non-differential input. The input of the amplifier is made on the emitter of an input transistor mounted in a common-base connection, converting the input voltage variations into current variations with a non-linear transfer curve that is, in principle, exponential or quadratic, these current variations being themselves copied, with a change in sign, into a second transistor and then converted by a third transistor into voltage variations with a non-linear transfer curve that is reciprocal to the previous one, this curve being in principle a logarithmic or square-root curve, and the voltage at the terminals of the third transistor being used as a feedback applied to the base of the first transistor. Application to the making of HF or IF input amplifier stages having a low noise factor and a wide dynamic range.

Abstract: A photoconductor-based electrical switch comprises an element made of photoconductor material possessing two electrodes located. on either side of an active zone, at least one light source emitting at least one light beam illuminating the active zone, the beam having a wavelength corresponding to a level of photon energy lower than the bandgap energy of the photoconductor material, the intensity of the light beam being such that there is a combination of the energy of at least two photons in the photoconductor material, in such a way that a mechanism of two-photon absorption in the photoconductor material contributes to the creation of carriers enabling the photoconductor material to be made conductive.

Abstract: A Deramp type radar used in synthetic aperture radar for radar imaging transmits coherently repeated linear frequency-modulated pulses and carries out a sort of pulse compression in reception by demodulation of the echo signals received by means of a frequency ramp that reproduces all or part of a transmitted pulse, and by a Fourier transform performed in range. With this type of pulse compression, a parasitic phase modulation appears on the signal delivered by a Deramp type radar. This parasitic phase modulation disturbs the standard SAR procession operations for the construction of radar images. The proposed method is used to eliminate the detrimental effects of this parasitic phase modulation on the construction of a radar image.

Abstract: The disclosed device, placed within an ATM packet switch, is of the type comprising a multiplexer associated with a specified number of input and output buffers and a device to control the internal flows of ATM cells informing the input buffers of the state of congestion of the output buffers. This device further comprises means to convert the flow of sporadic point-to-multipoint cells, arriving at the input of the input buffers, into a regular flow of point-to-multipoint cells towards the multiplexer irrespective of the outgoing direction taken by the cells and independently for each input.

Abstract: The invention relates to a highly selective chemical sensor comprising an acoustic wave transducer and a sensitive layer of so-called "molecular fingerprint" material. This is a macroporous crosslinked material having cavities whose steric and functional configuration is specifically suited to capturing molecular and/or ionic species.

Abstract: The disclosure relates to a mass memory with very large-scale integration as well as to a method for the manufacture of such a memory.

Abstract: The invention relates to towed acoustic transmitters forming an underwater vehicle which is itself intended for towing a linear acoustic receiving array (105). It consists in placing the vertical faired acoustic array (303) of such a transmitter at the very rear of the underwater vehicle, and in balancing the weight of this array by a faired ballast (313) situated at the very front thereof. These two parts are joined by a girder (310) of small cross-section, and the center of gravity of the whole is situated at the front of this girder and beneath it. The vehicle is towed by a cable (101) fastened to the vehicle by a hook (314) fixed to a swivel joint (315) above the center of gravity. It makes it possible to facilitate the operations of submersion and fishing-out of the whole while also achieving a greater depth of submersion.

Abstract: To carry out a fast recognition of objects, for example during a sorting operation, the measured parameters of these objects are divided into several classes. A rough sorting operation is done, taking account of the main classes. Then, for each class, the partial likelihoods of the measured parameters are measured and, finally, the overall likelihood is determined.

Abstract: A coder/decoder including a device for constructing from the preceding decoded image and from the current source image two pyramids of images of unlike resolution. Each pyramid contains the same number of images ordered identically according to their resolution. Each image corresponds to a level of resolution which is half as large in the horizontal and vertical directions of the image as a preceding level of resolution. Each pyramid is applied to a first and second serial input of the hierarchical motion estimator which outputs a motion vector having a magnitude which is proportional to the estimated motion between the two pyramids.

Abstract: Disclosed are a method and a system for the securing of the transmission of data elements between a sensor delivering pulses and a recorder processing these pulses. This method and system are applicable especially to a chronotachograph for heavy road vehicles. The principle of the disclosed method relies on a permanent exchange of enciphered data elements between a recorder module comprising the recorder and a sensor module comprising the sensor. The exchange is done at the initiative of the recorder module which sends command messages X?C(M.sub.C)! enciphered according to a first code C to the sensor module. The sensor module acknowledges the command and then, in turn, generates enciphered return messages X?C'(M.sub.R)!, either in order to indicate the acknowledgement of the command or to transmit pulses from the sensor with a view to their processing by the recorder. The recorder module then deciphers and verifies the return messages (M.sub.