Thomson-csf

Philippe Defranould

Jean-Pierre Huignard

Charles Maerfeld

Jean Desbois

Bernard Munier

Claude Poncot

Marc Verroust

A delay device for a frequency signal comprises an element made of acousto-optical material, provided with a first piezo-electric transducer transmitting an acoustic signal in the element and with a second piezoelectric transducer capable of detecting an acoustic wave. A light beam goes through the element and creates a field charge in the element. This charge field plays the role of a reflector for the acoustic wave transmitted by the transducer. By translating the beam along the direction Z, the propagation time of the transmitted acoustic wave is made to vary.

Acoustic wave delay system with an optically controlled delay medium

The transducer is chiefly designed to generate acoustic waves in the microwave range in a crystalline support of a bulk wave delay line or a Bragg cell. The transducer has a plane contact region of a ground electrode partially covering a face of the substrate, a piezoelectric plate on the contact region and a second electrode defining the piezoelectrically active region of the transducer. So as not to make a direct solder on the electrode and thus, in particular, reduce the admittance of the transducer as compared with known transducers, the second electrode is connected to a large connection region, placed on the support face, by a link bridge. The connection region supports the connection by soldering. The admittance is thus independent of the thickness of the solder.

Piezoelectric transducer to generate bulk waves

Method for the elimination of spurious echos in electro-acoustic delay

The device comprises a silicon substrate, means for generating a pulse elastic wave at the surface of the substrate on to which the image for read-out is projected, and elementary detectors detecting the conductivity of the substrate. Each of the detectors is constituted, in one embodiment, by two conductive bands arranged at a short interval from one another, perpendicularly to the direction of propagation of the elastic wave; a potential difference is applied between the conductive bands. The elementary detectors then sequentially furnish an electrical signal resulting at each point on the substrate from the superimposition on the one hand of the conductivity due to the image by photoelectric effect, and on the other of the conductivity due to the elastic wave by piezo-resistive effect.

Piezo-resistive device for the electrical read-out of an optical image

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.

Method and a device for an electro-acoustic reading of an optical device

A reading device for analysing an optical image in one dimension and for converting it into an electrical signal the amplitude of which characterizes the light intensity of the elemental zones analysed by a semiconductive substrate and scanned by the interaction of acoustic surface waves on a piezoelectric substrate, which comprises, for increasing its sensitivity, discrete junctions on the surface of the photosensitive semiconductive substrate 'scanned' by the surface waves arising out of the non-linear interaction, and wherein the output signal is collected between an electrode disposed on the other surface of the semiconductive substrate and an electrode of the piezoelectric substrate.

Electro-acoustic devices for analysing optical image

A device for reading two-dimensional optical images. It comprises a piezoelectric substrate on which two transducers transmit elastic waves in two separate directions, and a semiconductive and photoconductive layer arranged near the surface of the substrate, in which a nonlinear interaction occurs opposite the point where the two said directions converge. This point of convergence forms a reading point of the image which is projected onto the photoconductor, this point moving as a function of time along a straight line which forms an analysis line of said image.

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Paris, France

Philippe Defranould