Thomson-csf

Pierre Leclerc

Michel Hareng

Serge Le Berre

Jean-Pierre Huignard

Claude Puech

Robert Hehlen

Michel Papuchon

Jean-Noel Perbet

Philippe Marcenac

Francois Micheron

Didier Pribat

Dominique Broussoux

Baudouin De Cremoux

Pierre Legagneux

Jean N Perbet

Alain Friederich

Jean-Claude Carballes

Pierre Hirtz

Christian Collet

Marie A Di Forte

Philippe Aubourg

Jean L Bruneel

Michel C Ceccaldi

Armand Nappo

Pierre Lallemand

Serge LeBerre

A method of growth according to which a layer of a material having apertures is made on the surface of a substrate. A material is deposited in each aperture. When this material is liquid, it can absorb the material to be grown. Then, the growth is done in vapor phase. The material of the layer is chosen in such a way that there is neither growth nor nucleation on its surface during the growth in vapor phase. The disclosed method can be applied to the making of crystal whiskers positioned with precision, and to the making of tip type microcathodes.

Method for the controlled growth of crystal whiskers and application

An optoelectronic detector using a photodetector (1) and a stress induction device for inducing elastic waves with the stress inducing device being mechanically coupled to the photodetector. The stress inducing device includes an excitation which permits the transmission of the elastic waves.

Semiconductor optoelectronic detector

A device to eliminate ice formed on the surface of a wall, notably on the surface of an optical or radio-electric window, comprises a piezoelectric material having a vibrating active surface that mechanically cooperates with the wall to be de-iced, and means for the polarization of this piezoelectric material, comprising an AC voltage source and conducting or semiconducting electrodes placed in contact with this material according to a geometry capable of generating, within this material, an acoustic wave that has a direction of vibration which is oriented longitudinally and/or transversally to said surface to be de-iced, the amplitude of this vibration being sufficient to respectively detach and/or break the deposit of ice formed on said surface. The piezoelectric material is preferably a ferroelectric polymer such as a polymer of the group comprising PVF.sub.2, PVF.sub.2 -TrFE, PVDCN-VAc, PVF.sub.2 -TFE and the mixture of these polymers with one another and/or with PMMA or PEMA. The electrodes are preferably formed into a thin layer deposited on the surface of the piezoelectric material, and their material is then advantageously a material of the group comprising resistive indium-tin oxide, the polymers that are conductive in a matrix, hydrogenated amorphous silicon and polyimides charged with organic salts.

Device for the removal of the ice formed on the surface of a wall,

The invention relates to display devices with a mixed thermal and electrical effect. The invention relates to a special addressing mode making it possible to display a writing line, while limiting the control voltages to be applied from the outside to the display screen.

Thermoelectric effect display device

An image contained in an incident signal is displayed on a screen forming part of a matrix-access display device. The device is primarily applicable to high-definition or small-area screens designed for operation in the transmission mode, and is controlled by an optical system. Optical addressing of a line array and a column array of electrodes is performed by means of light beams which serve to illuminate photodetectors.

Electrooptical switching device

The invention relates to planar display screens and more particularly to smectic liquid crystal screens. One of the problems of high definition display screens (approximately 100 to 1000 lines and columns) is caused by the devices for controlling the heating current on the lines. The complexity of the installation and costs limit the increase in the definition. The invention arranges the N lines of a screen into .sqroot.N groups of lines supplied at each of their ends by .sqroot.N control devices functioning sequentially, i.e. 2.sqroot.N devices in all. Moreover, each line has a diode placed between the heating resistor and the common point of the circuit. Application to the display of images transmitted in the form of a video signal for television and display peripheral equipment in teletransmission.

Control device for a display screen and display screen controlled by

A Switch is disclosed which makes it possible to optically connect at least one of the circuits of a group of input circuits to at least one circuit of a group of output circuits. A photosensitive medium is illuminated by parallel beams from a matrix of input circuits which beams are then defracted on layers written in the medium and then reach one of the circuits of the matrix of photoreceiver circuits. The layers are written by interference of two beams whose wavelengths differ from that of input beams with the wavelength of the input beams being out of the spectral sensitivity range of the photosensitive medium.

Switching device for optical beams and telephone exchange incorporating

A liquid crystal visual display with a liquid crystal layer between two plates and resistive lines between one of the plates and the liquid crystal layer for heating the crystal to produce a display. The thermal diffusivity of the plate supporting the lines is below a value making possible viewing with the naked eye, for example 2.times.10.sup.-2 cm.sup.2 /s.

Liquid crystal visual display unit and telephone terminal incorporating

The invention relates to an optical printing device with unity magnification using coherent light and making it possible to significantly reduce speckle on the print. It relates to a printing device comprising a device for illuminating the object, a device receiving the object wave and in real time restoring a wave phase conjugate with the object wave to form a real image of the object. The printing device also comprises a photosensitive support placed in the image plane. The object illuminating device forms on the object to be reprinted a lighting spot which is of small size compared with the object, and the printing device also comprises scanning means for completely scanning the object a number of times by the lighting spot so as to superimpose a large number of images of the same zone having uncorrelated noises on the photosensitive support. The invention, more particularly, finds application in the printing of high resolution masks and large surface areas.

Optical device for printing planar objects

The hydrophone has an interferometer structure incorporating a measuring arm in which is provided a very long monomodal optical fibre immersed in the interaction medium in which is propagated the acoustic wave. A phase displacement is induced on the optical wave by the elastooptical effect and said wave is propagated in the fibre by the acoustic wave which creates an acoustic pressure field in the medium. A reference arm establishes a reference optical path and the phase displacement linked with the acoustic wave is detected by interferometry between the two optical waves emerging from the two arms. The optical connections between the source, the optical fibre immersed in the interaction medium, the reference arm and the detector being provided in guided optics in a compact structure.

Monomodal optical fibre hydrophone operating by the elastooptical effect

A telecopying process and a transmitter-receiver telecopier employing this process. A cell having a smectic liquid crystal is used for recording by thermo-optically forming an intermediate image of a linear element (column portion or a whole line) of the transmitted document, which image is thereafter projected onto a photosensitive surface. The same optical system permits, when transmitting, the reading of this linear element by a mosaic of detectors and, when receiving, the projection onto the photosensitive surface of the intermediate image recorded in the cell.

Telecopying process employing a cell having a smectic liquid crystal and

A system comprising means for emitting an analysis beam and a recording beam, the two beams being deflected by common deflection means. The analysis beam scans the document carrying the image to be analyzed and a detecting photocell provides an electrical signal. The recording beam scans a liquid crystal cell, where it records the image in synchronism with analysis in dependence upon a modulation of the thermo-optical effects induced in the liquid crystal. This modulation is provided by the electrical signal.

System for the analysis and the recording of monochromic images

The invention relates to a compact optical structure comprising a semiconductor emitter junction, a laser or a light emitting diode, coupled to a plane waveguide formed by a layer of photo-polymer deposited on a substrate with a suitable index. A surface layer, of photo-polymer for example, enables the registration of photo-induced diffraction structures performing particular optical functions such as that of a distributed reflector, deflector or lens. Such compact structures are applicable, in particular to the designing of simple, small devices, laser sources with distributed external resonators, interferometric gyrometers, hydrophones, multiplexers or demultiplexers.

Compact optical structure with integrated source

The invention relates to a semiconductor laser with a distributed reflector comprising a semiconductor junction, one of whose semi-transparent mirrors is a split face of the semiconductor in which is integrated a light emitting junction with epitaxial layers. The active layer of this junction is coupled to a waveguide integrated in a dielectric medium, on one face of which is engraved a grating forming a distributed reflector playing the part of the second mirror. The reflector, when functioning according the second order of counter coupling emits a diffracted wave normal to the waveguide which can easily be coupled to an optical fiber.

Laser with distributed reflector

In a liquid-crystal display device, a smectic liquid-crystal layer and a layer of photoconductive material are placed between two transparent plates. A voltage is applied to the photoconductor by means of electrodes while scanning the photoconductor with a writing light beam. At locations in which the resistance of the photoconductor is reduced under the action of the light beam, the heat generated causes transition of the liquid crystal to the isotropic state. The light-scattering action produced by subsequent cooling of the liquid crystal has the effect of writing the image to be displayed.

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Paris, France

Pierre Leclerc