Abstract: Ultrasound imaging pack composed of a hardware part for ultrasound imaging preprocessing and of a software part intended to be installed on a microcomputer, the hardware part including at least one ultrasound probe connected to a module of electronic circuits at least part of which is configurable, this module comprising analog FEC circuits, an assembly of analog/digital converters, an array of logic electronic gates and a high throughput link between this module and the microcomputer, the software part being stored on a removable medium.

Abstract: A curved bar probe (1) for an echograph is fabricated by using a thin support (2) on which is placed a bar of piezoelectric crystal. The bar is divided into a plurality of piezoelectric transducers elements (3). The thin support presents the particularity of being rigid at room temperature but is thermodeformable. By subjecting it to a heating-cooling cycle during which it is given a desired curved shape, a rigid bar having an imposed curved shape is obtained. It is then possible to avoid the adhesion of said support to a base (16). This would form a back-reflecting surface for acoustic waves and would create interference harmful to the useful acoustic signal.

Abstract: In a device for shifting the frequency of an optical wave, two optical waveguides coupled by an optical wave which propagates in the symmetric mode are excited and subjected to the action of an electromagnetic traveling wave having the effect of shifting the frequency of the optical wave which undergoes a transition from the symmetric mode to the antisymmetric mode. A transfer device supplied with a direct-current voltage V.sub.O serves to re-convert the antisymmetric mode to the symmetric mode in order to add the two light signals and to obtain a single output signal translated by the frequency F. This permits the construction of BLU optical modulators.

Abstract: Disclosed is a probe for medical echography wherein, between the piezoelectric transducers and the backing, there is inserted a half-wave strip at the natural resonance frequency of these transducers, thus enabling the use of the probe in two distinct frequencies, one of which is substantially equal to half the other, and thus providing for ordinary mode B imaging and DFM Doppler imaging with one and the same probe.

Abstract: An echography probe wherein homogenization of the directivity of the points of the strip. The material constituting the strip possesses a coefficient of absorption which depends on the frequency. The profile of the strip is determined by the knowledge of the law of the variation of this coefficient of absorption as a function of the frequency. It is shown that the pattern of directivity of a probe fitted with a strip of this type is independent of the working frequency.The invention finds particular application in medical echography for tissue characterization.

Abstract: Ultrasonic sensor and echograph with static sectorial scanning, especially for a wide angle picture, wherein according to a possible embodiment, the sensor comprises several groups of transducer elements forming between one another obtuse angles in such a way as to define overall a convex outline so that the delays or lags necessary to obtain a complete scanning be lower than with a conventional linear strip and thus easier to contol, the sensor being intended to be applied to medical echography.

Abstract: A directional velocity hydrophone is provided which does not appreciably disturb the particular movement of the fluid in which it is plunged and which comprises bending blades disposed in a ring and embedded in an inertial mass, which deliver an electric current substantially proportional to the particular speed of the fluid.

Abstract: A dispersive acoustic delay line using reflection on slanted gratings is provided. This device comprises slanting input and output transducers each formed of pair electrode fingers. The interval of the electrodes of different polarity varying from nv/2f.sub.min to nv/2f.sub.max, where v is the speed of the waves, f.sub.min and f.sub.max the endmost frequencies of the frequency band and n the number of the harmonic on which the transducers operate. The interval of the gratings varies from kv/f.sub.min to kv/f.sub.max, where k is the number of the operating harmonic of the network, with n.noteq.k.

Abstract: A convolver based on the propagation of acoustic waves at the surface of a piezoelectric solid comprises a piezoelectric substrate, means for exciting two backward-traveling acoustic waves at the frequency f, means consisting of at least two electrodes for collecting the signal at the frequency 2f, the signal being produced as a result of nonlinear interaction of the two acoustic waves. The convolver device is connected to one of the two electrodes by means of a plurality of electrical contacts placed lengthwise and at intervals along the axis of propagation of the two interacting acoustic waves which are representative of the electrical signals applied to the two convolver inputs.

Abstract: An acousto-electrical device for storing and processing information, in analog form, at any point of a two dimensional surface. It comprises: a piezoelectric substrate carrying four electro-mechanical transducers emitting elastic surface waves in two normal directions; a semi-conductor substrate carrying a diode network placed facing the piezoelectric substrate, and two electrodes placed respectively on the end faces of the two substrates. In one embodiment, the storing of a signal applied between the electrodes is achieved by means of two elastic auxiliary addressing waves, the non linear interaction of these three signals supplying a spatially periodic signal independent of time which is stored by the diodes. The stored signal is subsequently processed by means of elastic reading waves which interact non linearly therewith to provide simple reading of the initial signal or processing thereof, in particular its Fourier transform.

Abstract: A device capable of operating over a wide frequency band with a constant angular width of the radiation lobe of elastic waves. It comprises in combination at least one omnidirectional reversible electroacoustic transducer and an assembly of reflecting surfaces of zero acoustic impedance which define a space inside which said transducer is arranged.

Abstract: The invention discloses an elastic wave accelerometer for measuring acceleration at least in one direction.The device comprises a solid support, a seismic mass and a piezoelectric wafer embedded in the seismic mass and in the solid support. An acceleration in one direction in the plane of the wafer produces an extension in one portion of the wafer and a compression in the other. Elastic waves are excited in the two portions of the wafer. Two oscillators are obtained by means of amplifiers and the frequency difference between the two oscillators is proportional to the acceleration.The invention applies to accelerometers for inertial navigation.

Abstract: The device comprises a piezoelectric medium associated with a semiconducting and photosensitive medium on which the optical image is projected. Four transducers placed on the piezoelectric medium emit four elastic waves in two distinct directions with wave numbers such that the signal resulting from the interaction of these waves has a zero wave number. Depending on the waveform of the signals applied to the transducers, it is possible to obtain either point-by-point reading of the image or the Fourier transform of said image.

Abstract: A device for memorizing information by means of interactions between elastic waves and electromagnetic waves. It comprises a piezoelectric substrate, at least one electromechanical transducer receiving the information to be memorized, means for exciting a pulsating electric field through the substrate, said field interacting non-linearly with the elastic wave created by the transducer to form a spatial charge pattern representing said information and means for modifying the physical properties of the medium of propagation of the elastic waves in the region of said pattern, for memorizing. The reading is effected by a non-linear interaction between said pattern and the pulsating electric field.

Abstract: A system realizing various processings of signals, depending on the nature, duration and form of these signals, by means of non-linear interactions between elastic surface waves or between elastic and electromagnetic waves. The system realizes the memorization of the correlation function between a first signal, which is an elastic surface wave, and a second signal which is either an electromagnetic or an elastic surface wave; the reading may be realized with an electromagnetic wave or an elastic surface wave whose pulsation equals or not that which corresponds to the spatial period of the memorized signal, thus generating correlation or convolution functions.

Abstract: A system realizing various processings of signals, depending on the nature, duration and form of these signals, by means of non-linear interactions between elastic surface waves or between elastic and electromagnetic waves. The system realizes the memorization of the correlation function between a first signal, which is an elastic surface wave, and a second signal which is either an electromagnetic or an elastic surface wave; the reading may be realized with an electromagnetic wave or an elastic surface wave whose angular frequency equals or not that which corresponds to the spatial period of the memorized signal, thus generating correlation or convolution functions.

Abstract: A method and a device for the one-dimensional analysis of an optical image and its conversion into an electrical signal, of which the amplitude characterizes the luminous intensity at each point. The device comprises, disposed opposite one another, a piezoelectric substrate and a semiconductive substrate onto which the image is projected. Reading is effected in two steps; the first step supplies a stationary distribution (q) of charges in the semiconductor by scanning the image by a non-linear interaction between two elastic waves; the second step, carried out after an integration time .DELTA.t of the image gives a reading signal arising out of the non-linear interaction between a third elastic pulse and the charge distribution (q) as modified by the incident illumination during the time .DELTA.t.

Abstract: The invention concerns acoustic surface wave devices with multistrip couplers. The coupler of such a device comprises two arrays of N conductive strips connected by a connecting array and having at least one characteristic, such as for example their periodicity which is distinct for the two arrays. In modifying, for example, the ratio p.sub.1 /p.sub.2 of the periodicities of the arrays, the operation of this device is modified. This device permits in particular the construction, for wide frequency bands of utilisation of n dB couplers, energy concentrators or unidirectional transducers.