Thomson-Csf

Fastlite

Thomson-Cgr

Daniel Kaplan

Pierre Tournois

Thomas Oksenhendler

Pierre Landouar

Jean-Claude Lehureau

Jean-Paul Pocholle

Georges Mourier

Guy Aubert

Gonzalo Velasco

Emmanuel Rosencher

Borge Vinter

Alain Friederich

Vincent Berger

Nicolas Forget

Thibaut De Saxce

Georges Roux

Francedillaois Micheron

Manuel Joffre

Nicole Sol

Olaf Schubert

Patrick Herbet

Mieczylaw Hildebrandt

Philippe Boulanger

Eric Criton

Franck Lacassie

Marcel A Bouvier

Rupert Huber

Raman Maksimenka

A method and a system for scanning a time delay between a first ultrafast optical pulse of duration shorter than 10 ps and a second ultrafast optical pulse of duration shorter than 10 ps, wherein the second ultrafast pulse is submitted to an acousto-optic Bragg diffraction by an acoustic pulse in the bulk of an acousto-optic material and the delay scanning is produced by time variation of the acoustic pulse in the material.

Rapid optical delay scanning method and apparatus using time dependence of acousto-optic diffraction

The invention relates to a device for compensating the temporary scattering applied to the generation of ultra-short light pulses, said device including two identical and parallel optical diffraction gratings RA, RB and two identical prisms PA, PB that are placed inside the above-mentioned optical diffraction gratings RA, RB, given that the above-mentioned optical diffraction gratings RA, RB are volume phase gratings that function, during transmission, on the principle of Bragg diffraction. The outer surfaces FeA, FeB of the above-mentioned prisms PA, PB are parallel to the above-mentioned optical diffraction gratings RA, RB, and the inner surfaces FiA, FiB of the above-mentioned prisms PA, PB are parallel therebetween.

Device for compensation of time dispersion applied to the generation of ultrashort light pulses

The method and device for measuring the spectral phase or combined spectral and spatial phases of ultra short light pulses, consisting of a decomposition of the light pulse to be measured in two identical replicas called signal pulse and primary reference pulse, respectively, of different polarization or direction and the phase characteristics of which are essentially identical to the original pulse, a temporal filtering of the primary reference pulse by a nonlinear interaction generating a secondary reference pulse of average frequency essentially identical and of spectral width greater than the spectral width of the primary reference pulse, and a spectral interferometry measurement by recombination of this secondary reference pulse and the signal pulse with a given temporal offset.

Method and device for measuring the spectral phase or the combined spectral and spatial phases of ultra short light pulses

The invention relates to a method and device for controlling the amplitude of the wavelength spectrum of ultra-short light pulses emitted by multipass laser amplifiers. According to the invention, a programmable acousto-optic device () is introduced into a laser cavity of a multipass amplifier (), in order to modify slightly the amplitude of the spectrum of the light pulse with each passage, owing to a collinear or quasi-collinear interaction between the light pulse and a sound beam, the result from the filtering being used on the non-diffracted direct light beam from the acousto-optic interaction.

Method and device for controlling the amplitude of the wavelength spectrum of ultra-short light pulses emitted by multiple passage laser amplifiers

Device for dispersion of light pulses of an optical beam constituted by two dispersive prisms with the same vertex angle, mounted head to tail, the optical input surface of the first prism being parallel to the optical output surface of the second prism, the distance separating the optical input surface of the first prism and the optical output surface of the second prism being adjustable, given that the material constituting at least one of the first and second prisms is an acousto-optic material allowing for acousto-optic interaction between the optical beam and an acoustic beam, the acoustic wave of the acoustic beam generating, in at least one of the first and second prisms, an integrated deflective Bragg cell.

Device for dispersing light pulses of which the spectral amplitude is programmable

A method for measuring ultrashort light pulse which comprises a first step of linear optical filtering of the signal for which it is desired to measure the amplitude of the pulses by means of an acoustic interaction between the optical signal and a colinear or quasi-colinear acoustic beam, a second step of either mixing in a non-linear response electro-optical element of optical beams diffracted by the acoustic beam, followed by one detector for detecting the light intensity derived from the mixer, or effecting one integration detection of the square of the optical intensity diffracted by the acoustic beam.

Method and device for measuring the phase and amplitude of ultrashort light pulses

A detector with quantum structure comprising a small-gap semiconductor material inserted between two large-gap semiconductor materials, the structure comprising a coupling grating between the wave to be detected and the detector zone constituted by the small-gap material. Under these conditions, the detector zone may have a very small thickness (typically of the order of 1,000 .ANG.) and lead to a detectivity, limited by the dark current, that is high.

Infrared detector with non-cooled quantum well structure

A sweep generator circuit generates a primary pulsed voltage and a secondary voltage which are applied to the deflection plates of a streak camera. A primary pulsed voltage generator includes at least one light operated switch for producing deflection of an electron beam in one direction. A secondary voltage generator means generates the secondary voltage which causes deflection of the electron beam in an opposite direction. Variations in the incident light intensity create substantially identical fluctuations in the deflection of the electron beam produced by the primary pulsed voltage and the secondary voltage. Additionally, any variations with respect to time in the deflection of the electron beam produced by the secondary voltage are small in comparison with variations in the deflection of the electron beam produced by the primary pulsed voltage. The sweep generator circuit has an operating point that is stable with respect to variations in the light intensity.

Sweep generator circuit for a streak camera

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.

Photoconductor-based electrical switch

Back-projection display system and method for making a back-projection

Method of regulating the magnetic field delivered by a resistive magnet,

The invention provides a method and device for forming images by nuclear magnetic resonance in which an image is constructed by discrimination of the intrinsic parameters of the tissues examined. The image is formed by putting forward the degrees of attachment and mobility of the nuclei of the tissues. The parameters displayed represent the field heterogeneities at the microscopic and molecular levels. The method consists in acquiring a first image using conventional methods then, after slightly varying the orientater magnetic field, in acquiring another image using the same methods. Then an image of another type is formed by representing the relative variations of the relaxation times between this first and this second image.

Method and device for forming images by nuclear magnetic resonance

A solar cell comprises a first sealed glass envelope on which is deposited a solar radiation-absorbing material and a second sealed envelope placed around the first envelope in such a way that a space is created between the two envelopes in which a very low pressure is established, whereby the solar energy-absorbing material according to the invention is formed by at least one layer of a glass - metal compound covered by a layer of the oxides of the said metal.

Solar cell and method for the manufacture thereof

The process consists of introducing into the silicon-containing layer at the same time as silicon deposition, another element of column IVa of the periodic classification in a proportion equal to or below 5% of the number of silicon atoms and greater than 0.1%. According to a preferred variant, this element is germanium. Deposition takes place at a temperature close to the crystallization temperature T. The process can comprise a subsequent phase during which the deposited layer undergoes heat treatment in an atmosphere of a plasma containing hydrogen or one of its isotopes at a temperature below the crystallization temperature T of the layer.

Process for producing a layer containing silicon

Process for producing layers of silicon or one of its alloys in pure or doped form and able to absorb optical radiation, the layers being of limited thickness, it comprising a first stage of depositing the layer by chemical decomposition of a gaseous mixture containing silane at a temperature close to the crystallization temperature and a second stage of treating in a hydrogen plasma at a lower temperature.

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Paris, France

Daniel Kaplan