Thomson-csf

Thales

Centre National De La Recherche Scientifique

Université Nice Sophia Antipolis

General Electric Cgr S.a.

Université De Paris

Institut D'optique

Université Pierre Et Marie Curie (paris 6)

Université Des Sciences Et Technologies De Lille

Daniel Dolfi

Jean-Pierre Huignard

Martine Doisy

Umberto Bortolozzo

Stefania Residori

Pierre Tournois

Jean Chazelas

Arnaud Peigne

Jean-Claude Lehureau

Francois Micheron

Jean-Paul Pocholle

Brigitte Loiseaux

Dominique Broussoux

Carlo Sirtori

Stéphanie Molin

Jean-Marc Bureau

Yves Canal

Jean-Luc Ayral

Arnaud Brignon

Philippe Refregier

Patrick Feneyrou

Gérard Berginc

Mehdi Alouini

Jérôme Bourderionnet

Sylvain Combrie

Charlotte Tripon-Canseliet

Philippe Souchay

Vincent Laude

Pascal Joffre

Michele Labeyrie

Thomas Merlet

Renaud Bouffaron

Paul Sergent

Olivier Maas

Loic Morvan

Sylvain Lazare

Jean-Charles Beugnot

François Goudail

Vincent Magnin

Remy Braive

Isabelle Robert

Didier Decoster

Cindy Bellanger

Sarah Benchabane

Arnaud Beniere

Loïc Morvan

Grégoire Pillet

El Hadj Dogheche

A method for processing a signal from a coherent lidar comprising a periodically frequency-modulated coherent source (L), the method includes the following steps: A decomposing each modulation period indexed j into a plurality of intervals indexed i, and determining, for each interval Iij, an elementary power spectral density DSP(i,j) of the beat signal over the interval, B determining an average power spectral density over j DSP(i), C determining a lower frequency bound of the average power density DSP(i) and an upper frequency bound, D determining a distance dk(i) and a velocity of the fluid vk(i) from the lower and upper bounds.

Frequency-modulated coherent lidar

A distributed optical fiber sensor of dynamic stress state comprises: an optical assembly configured to generate a series of optical pulses; an optical fiber of optical length L; an optical system configured to: inject through the first end at least the series of optical pulses; receive at the level of the end at least one series of output optical pulses, arising from the input pulses after propagation and retro-propagation in the fiber; generate at least one continuous reference beam or reference optical pulses on the basis of the optical assembly or of output optical pulses; produce a series of interference zones corresponding to the interference between the reference beam or a reference pulse and a signal optical pulse arising from an output optical pulse; a holographic detector comprising: a liquid-crystal light valve, the valve disposed so that it at least partially covers the interference zones, and producing holograms on the basis of the interference zones; at least one optical detector configured to detect output optical signals diffracted by the holograms.

Distributed optical fibre sensor for sensing stress state

This oscillator comprises: a source generating an incident optical wave at a pulsation frequency &#x3c9;; an optomechanical resonator, having optical resonances at the pulsation frequency &#x3c9; and mechanical resonances at a frequency fand generating, from the incident optical wave, emergent optical waves at the pulsation frequencies &#x3c9; and &#x3c9;&#x2212;2&#x3c0;f, and an acoustic wave at frequency f; and, a photodiode delivering a useful signal at frequency ffrom the emergent waves. This oscillator further comprises: an acoustic propagation means for propagating the acoustic wave over a distance in order to produce a delayed acoustic wave; a means for converting the delayed acoustic wave into a delay signal at the frequency f; and, a control loop, processing the delay signal in order to obtain a control signal applied to the source.

Radio frequency oscillator

A fiber optic sensor for detecting an excitation in proximity to a fiber optic assembly, the excitation inducing a modulation of the phase of an optical signal propagating in the fiber optic assembly, the sensor comprises: a laser assembly emitting at least one laser beam; a fiber optic assembly; an optical system configured to: inject at least one portion of the laser beam; generate at least one laser signal beam issued from the laser beam injected into and propagated in the fiber assembly; generate at least one reference beam from the laser beam or the signal beam; produce at least one interference zone corresponding to the interference between a portion of the reference beam and a portion of the interference signal beam corresponding to the interference between a portion of the reference beam and a portion of the signal beam; a digital holography assembly comprising: a liquid-crystal spatial light modulator; a video camera configured to receive the interference zone and to transcribe it electrically to the liquid-crystal spatial light modulator in order to create thereon a phase hologram corresponding thereto; at least one optical detector configured to detect an output optical signal beam.

Optical fiber sensor

An optical fiber sensor for locating an excitation in proximity to an optical fiber assembly comprises: a laser assembly configured to emit N laser beams indexed i with N&#x3e;1, of respective emission wavelength &#x3bb;i, an optical fiber assembly comprising N successive sections indexed i, an optical system configured to: inject the laser beams, receive N signal beams indexed i respectively of wavelengths &#x3bb;i, generate N reference beams indexed i respectively of wavelengths &#x3bb;i, produce N interference areas indexed i, a holographic detector comprising: a liquid crystal light valve that at least partially covers the interference areas, and is configured to produce N holograms indexed i from, respectively, N interference areas, at least one optical detector configured to detect N output optical signals indexed I, a processing unit adapted to identify the section of the fiber assembly situated in proximity to the excitation to be located.

Sensor with high-sensitivity optical fiber having a holographic detector comprising a liquid crystal light valve

Techniques for identifying images of a scene including illuminating the scene with a beam of 3 or more wavelengths, polarized according to a determined direction; simultaneously acquiring for each wavelength an image X(&#x3bb;) polarized according to said direction and an image X(&#x3bb;) polarized according to a direction perpendicular to said direction, X(&#x3bb;) being spatially distinct from X(&#x3bb;); calculating for each wavelength an intensity image which is a linear combination of X(&#x3bb;) and X(&#x3bb;), providing an intensity spectrum for each pixel; calculating for each wavelength a polarization contrast image on the basis of an intensity ratio calculated as a function of X(&#x3bb;) and of X(&#x3bb;), providing a polarization contrast spectrum for each pixel; and calculating a spectro-polarimetric contrast image of the scene, each pixel of this spectro-polarimetric contrast image calculated based on the intensity spectrum and the contrast spectrum of the pixel considered.

Method for identifying a scene from multiple wavelength polarized images

The subject of the present invention is a dynamic sensor of physical quantities with optical waveguide with optically-pumped amplifier medium, which requires no interferometer or reference sensor and which makes it possible to obtain at least the same level of performance, in terms of sensitivity, as known sensors of this type, and this waveguide is linked at one end to a selective mirror, and comprises at its other end an interrogation laser, the reflection of which on the selective mirror produces a wave which, by interference with the incident wave, provokes the periodic saturation of the gain of the waveguide.

Dynamic sensor of physical quantities with optical waveguide with optically pumped amplifier medium

The general field of the invention is that of fiber-optic sensors comprising at least one measurement optical fiber having an optically pumped doped amplifying medium, the optical characteristics of which are sensitive to a physical quantity, the fiber having at least one Bragg grating. The fiber is designed so as to generate, in the amplifying medium, two optical waves having different optical frequencies that propagate in the same direction after reflection on the Bragg grating and are emitted by the amplifying medium, the two optical frequencies depending on the physical quantity. The two waves may be generated using either a birefringent polarization-maintaining fiber or a DBR (Distributed Bragg Reflector) laser cavity. Notably, this sensor may be used as a hydrophone.

Self-referenced optical fiber sensor and related sensor network

A synchronization device which synchronizes signals transmitted from a transmitter to receivers. The transmitter includes a generator for generating a synchronization signal having a recurrence period substantially equal to the minimum resolution of the journey time between the transmitter and the receiver. Each receiver includes a controllable delay for delaying the synchronization signal and a synchronization loop downstream of the delay. The synchronization loop includes a semi-reflecting plate, a correlator and a device for slaving the delay depending on the correlation. A signal received by the receiver is synchronized when the correlation function of the two successive recurrences of the synchronization signal passing through the semi-reflecting plate is at a maximum. The device may be used for accurate synchronization of information distributed from a transmitter to mutually remote receivers, for example for operating complex electromagnetic or optical rigs.

Accurate synchronizing device

An optical control device for an electronic scanning antenna having at least two controlled radiating elements, and including means for providing first and second mixed light beams, the first light beam polarized according to a first direction and having a first wavelength (&lgr;,), and the second light beam, polarized according to a second direction and having a second wavelength (&lgr;,); at least two optical delay circuits each receiving the first and second mixed light beams and configured to induce complementary delays compared to a determined time value on the first and second beams; chromatic separators each situated at the output of a corresponding one of the delay circuits and configured to separate the light having the first wavelength (&lgr;,) from the light having the second wavelength (&lgr;,); first photodetectors each coupling a corresponding radiating element to a corresponding chromatic separator; second photodetectors each coupling a corresponding chromatic separator to a corresponding first mixer; and second mixers each of which is coupled to a corresponding first mixer, a corresponding radiating element, and a radar signal processor. The first and second light beams are modulated at a transmission frequency (f,) and each of the first mixers mixes the modulated transmission frequency (f,) and an intermediate frequency (f,) to provide a local oscillator frequency (f,) at an output of the first mixer, and the second mixer mixes the local oscillator frequency (f,) and a received signal from a corresponding radiating element including the transmission frequency (f,) and a Doppler frequency (f,) to provide an output frequency which comprises the intermediate frequency augmented by the Doppler frequency (f,&plus;f,) to the radar signal processor.

Optical control device for electronic scanning antenna

UHF phase shifter and application to an array antenna

Transverse electrical filter operating optically

Device for creating optical delays and application to an optical control

A device for the optical processing of electrical signals. An optical source (L) emits a multiple-wavelength optical beam (B1). A modulator (MOD) modulates this beam. An optical fiber (F) receives the modulated beam and delays the components corresponding to the different wavelengths differently. A dispersive grating disperses wavelengths contained in the modulated beam in different directions. A spatial light modulator controls the level of optical intensity of different directions of the dispersed beam. An optical detection system receives the beam processed by the spatial light modulator. Such a device may find particular application to a transverse filter and microwave signal correlator.

Device for the optical processing of electrical signals

An optical architecture enabling the intercorrelation of two instantaneous wideband temporal signals. The beam coming from a monomode laser is used to obtain two carriers (W1, W2) for signals R(t) and S(t) by the use of, for example, integrated optical modulators (mod1, mod2). These two carriers have orthogonal polarizations and are distributed in a 2D structure comprising spatial light modulators as well as polarization separator elements. P.times.P independent channels (Cl to Cn) are thus formed. Their detection on a matrix of photodetectors (modl to modn) makes it possible to obtain, on each of them, the intercorrelation signal for different delays of the signals R(t) and S(t).

Wideband intercorrelation method and device implementing this method

Growing community of inventors

Orsay, France

Daniel Dolfi