Cold-atom and light-pulse interferometric system and method, for the on-board measurement of acceleration or rotation

A cold-atom and light-pulse interferometric system, the interferometric system comprising a vacuum chamber, a laser source, a plane retro-reflective optical component, an electronic system and a detection system, the vacuum chamber being adapted to contain a cloud of cold atoms, the laser source being adapted to generate a sequence of laser pulses towards the cloud of cold atoms along an axis of the laser (uL), the retro-reflective optical component being arranged so as to reflect the sequence of laser pulses towards the cloud of cold atoms, the sequence of laser pulses comprising N successive light pulses, where N is an integer number higher than or equal to three, the successive light pulses of the sequence being temporally separated from each other by an interrogation time T;

• the retro-reflective optical component having a normal to its plane defining a measurement axis aligned with laser axis at an initial time instant of the sequence;
• the electronic system and the detection system being configured to carry out an inertial measurement of the cloud of atoms, by atom interferometry, along the measurement axis,
• wherein the interferometric system includes:
• an actuating device mechanically connecting the optical component to a plate, the plate being fixed with respect to the vacuum chamber, and at least one rotation sensor fixed with respect to the vacuum chamber, the at least one rotation sensor and the electronic system being suitable to provide at least one measurement of rotation of the vacuum chamber about at least one axis transverse to the laser axis at each interrogation time of said sequence, the electronic system and the actuating device being adapted to angularly tilt the optical component with respect to said plate during each interrogation time of said sequence, as a function of said at least one rotation measurement acquired by the rotation sensor during said interrogation time of said sequence, in order to compensate for a rotation of the vacuum chamber transversely to the laser axis at each successive light pulse of the sequence with respect to an orientation of the vacuum chamber at the initial time instant of the sequence.

A cold-atom and light-pulse interferometric method comprising the following steps:

• generating a sequence of laser pulses towards a cloud of cold atoms in a vacuum chamber, the sequence of laser pulses comprising N successive laser pulses, where N is an integer number higher than or equal to three, the successive light pulses of the sequence being timely separated by an interrogation time T, the light pulses being reflected on a plane retro-reflective optical component, a normal to the plane of the retro-reflective optical component defining a measurement axis and being aligned to the laser axis at an initial time instant of the sequence;
• at the end of the sequence of laser pulses, carrying out an inertial measurement of the cloud of atoms, by atom interferometry, along the measurement axis, the inertial measurement being integrated over the sequence of laser pulses;
• measuring at least a rotation of the vacuum chamber about at least one axis transverse to the laser axis at each interrogation time of said sequence;
• at each interrogation time, angularly tilting the optical component with respect to the vacuum chamber, as a function of the rotation measured during said interrogation time of said sequence, in order to compensate for a rotation of the vacuum chamber transversely to the laser axis at each successive light pulse of the sequence with respect to an orientation of the vacuum chamber at the initial time instant of the sequence.