Commissariat &#xc0; L'&#xc9;nergie Atomique Et Aux &#xc9;nergies Alternatives

Commissariat a L'energie Atomique

Safran

Jean-Michel Leger

Matthieu Le Prado

Nelly Kernevez

Sophie Morales

Jean-Jacques Chaillout

William Fourcault

Umberto Rossini

Bernard Guilhamat

Mathieu Baicry

Bruno Charrat

François Bertrand

Jaroslaw Rutkowski

Christophe Guttin

Ghislain Despesse

Olivier Gravrand

Marc Beranger

Mikael Carmona

Thomas Jager

Francois Bertrand

Augustin Palacios Laloy

Laurence Clerc

Mikaël Carmona

Jean Crescini

Alexandre Paleologue

Frederic Stoeckel

Etienne Brunstein

Marc Gramlich

Georges Remillieux

The invention relates to a navigational aid method for an inertial navigation system including at least one inertial sensor () having a sensitive axis (X-X), each inertial sensor () comprising an ASG gyroscope () able to deliver an ASG signal representative of a rotation about the corresponding sensitive axis (X-X), and a MEMS gyroscope () able to deliver a MEMS signal representative of a rotation about the corresponding sensitive axis (X-X), the method including the steps of: between a first date and a subsequent third date, calculating a path from the MEMS signals; from the third date, calculating the path from the ASG signals; estimating a bias vector introduced by the MEMS gyroscopes (), from the MEMS signals and ASG signals; at a fourth date subsequent to the third date, resetting the path.

Navigational aid method, computer program product and inertial navigation system therefor

An optical pumping and isotropic measurement magnetometer. The magnetometer is all-optical in the sense that resonance between Zeeman sub-levels is induced by modulating the intensity or the frequency of the pump beam. Resonance is detected either using the pump beam itself or an unmodulated probe beam. The pump beam is linearly polarised and its polarisation direction is kept constant relative to the direction of the magnetic field to be measured, so that a measurement independent of the orientation of the field can be made.

All-optical and isotropic magnetometer

A magnetometer including a detector configured to measure the amplitude of an output signal at an oscillation frequency to deduce a component of a magnetic field to be measured starting from the value of a resonance gradient, including a main excitation source outputting a measurement signal oscillating at a main oscillation frequency and a secondary excitation source outputting a reference signal with known amplitude oscillating at a secondary oscillation frequency, the detector being configured to measure the output signal amplitude at a harmonic of the secondary oscillation frequency and to deduce said resonance gradient. The invention also applies to a network of magnetometers and a method of measuring a magnetic field without slaving and compensation of fluctuations of the resonance gradient.

Magnetometer without slaving and with compensation for fluctuations in the resonance gradient in weak field, magnetometers network and measurement method

A device for measuring an electric field in a conducting medium, including: an insulating enclosure; first, second, and third pairs of electrodes, the electrodes of a same pair being arranged on opposite external walls of the enclosure, and the electrodes of the first, second, and third pairs being centered on first, second, and third orthogonal axes; a first conductive coil; a first pair of switches enabling to alternately connect the first coil between the electrodes of the first, of the second, and of the third pair of electrodes; and a single magnetometer.

Device for measuring an electric field in a conducting medium

A magnetic resonance optical pumping isotropic magnetometer including a laser, a gas filled cell, a HF discharge circuit, RF magnetic field generating coils surrounding the cell, a first frequency regulating mechanism of an RF generator, a second polarization regulating mechanism of the laser beam, and a third regulating mechanism of the direction of the RF magnetic field. The direction of polarization of the laser beam at an inlet of the cell is orthogonally aligned with the magnetic field to be measured by virtue of a liquid crystal polarization rotator. The magnetometer is well-adapted to an integrated arrangement.

Isotropic and integrated optical pumping magnetometer

A system including: a cable including: a core capable of transporting at least one useful electric signal; a sheath surrounding said core; at least one conductive wear detection strand embedded in the sheath and substantially extending along the entire length of the cable; and at least one reference conductive element which is not connected to said at least one wear detection strand and substantially extends along the entire cable length; and a control unit capable of measuring the capacitance or the resistance formed between said at least one strand and the reference conductive element.

Electric cable wear control system

The laser comprising an optical fiber having two ends of which a first whereby the light is to be received, and a doped section for absorbing at least part of the light received via the first end and emitting light, the method includes: applying a torsion angle to the optical fiber; supplying light having a pump power at the first end of the optical fiber; checking that the Polarization Extinction Ratio of the light output from the first end of the optical fiber remains greater than a predetermined value throughout a predetermined range of the pump power; and, if the Polarization Extinction Ratio remains greater than the predetermined value throughout the predetermined range of the pump power, attaching the optical fiber to a mechanical mount at two attachment points of the optical fiber situated on either side of the doped section, with the torsion angle applied to the optical fiber.

Method for manufacturing an optical fibre laser

A laser includes an optical fiber having two ends of which a first end is configured to receive light therethrough, and a doped section configured to absorb at least part of the light received by the first end and for emitting light. The laser further includes a heat-conducting material which coats at least the doped section of the optical fiber.

Optical fiber laser and method for manufacturing an optical fiber laser

This method makes it possible to carry out the auto-calibration of the electromagnetic coils of an apparatus such as an atomic clock, a magnetometer or a gyroscope by injecting successive currents into the coils and measuring the magnetic fields induced in order to calculate the transfer coefficients (field/current) of each of the coils and the real angles that they form with very great precision.

Method of calibrating an atomic-functioning apparatus

The present invention relates to a vector magnetometer for measuring the components of an ambient magnetic field. This vector magnetometer comprises an optically pumped scalar magnetometer ('), a pair of conductive windings (Ex,Ey) having distinct axes (Ox, Oy) and powered by two generators (Gx, Gy) having distinct frequencies. The RF coil () of the scalar magnetometer and the conductive windings (Ex,Ex) are mechanically integral with a swivel support () mounted on swivel means. The axis of the RF coil is in the same plane as the axes Ox, Oy. The support is swivelled so that this plane is substantially orthogonal to the ambient magnetic field.

High resolution and high precision vector magnetometer

This atomic clock comprises means for applying two mutually perpendicular oscillating magnetic fields (), governed by a control device () that makes them apply a static or nearly static magnetic field for compensating the ambient magnetic field in order to cancel sub-level energy variations of the matter, which disrupt the frequency of the returned photons and the reference provided by the clock. Traditional magnetic shielding may be omitted. Said device can also operate as a magnetometer.

Apparatus with ambient magnetic field correction

An atomic clock comprises helium 3 plasma as measurement medium, which is taken to the plasma state to exploit the metastable state of the material and the levels of the hyperfine structure, the lifetime of which is long and which thus enable an easier measurement than the excitations of gaseous atoms.

Atomic clock operating with helium 3

An atomic clock including a mechanism applying both a static magnetic field and two oscillating magnetic fields, all mutually perpendicular, in a magnetic shield. The amplitudes and frequencies of the oscillating magnetic fields may be chosen so as to annihilate energy variations between sub-transition levels of excited atoms and to reinforce a clock output signal, and with low sensitivity to defects in regulation.

Atomic clock regulated by a static field and two oscillating fields

A differential magnetometer consisting of at least one active coil () and a receiver coil () for which the windings are installed differentially, is provided with a measurement circuit () with a slaving device that corrects dissymmetry appearing between windings () to eliminate residual induction at the frequency of the magnetic excitation field, intended to make the measurement coil () more sensitive without applying a voltage to it.

Magnetometer with structure asymmetry correction

The magnetometer includes a magnetic core () with at least one branch (), at least one exciting coil () and one take-up coil () sensitive to ambient fields thanks to the excitation field (B). An additional magnetic field, to advantage perpendicular to the previous ones, is added to eliminate very low frequency noises, without it being measured.

Growing community of inventors

Villard Bonnot, France

Jean-Michel Leger