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Frederic Mosca

Gilles Grosso

Guillaume Matte

Yann Cottreau

Samuel Thomas

Marcel Vial

Pascal Girardi

Gilles Greninguey

Robert Girault

An electroacoustic transducer submersible in an immersion fluid () for underwater acoustic communications, includes two horns (), a counterweight (), two electroacoustic motors (), aligned along an axis of symmetry (), the opposite ends of the motors being respectively connected to a horn, the unit consisted by the electroacoustic motors, the counterweight and the horns being able to generate a longitudinal electroacoustic resonance mode. The transducer includes a rigid and hollow cylindrical part () extending around the counterweight, the cylindrical part having an axis merged with the symmetry axis of the transducer, the inside of the cylindrical part forming a fluid cavity able to be filled with the immersion fluid, the electroacoustic motors and the cylindrical part being so dimensioned that the fluid cavity forms an acoustic coupling between the longitudinal electroacoustic resonance mode and a circumferential resonance mode of the cylindrical part.

Low frequency electro acoustic transducer and method of generating acoustic waves

An acoustic antenna includes an array of elementary submarine transducers, each elementary transducer including, between a counterweight and a horn, at least one ceramic. Each elementary transducer is mounted on a printed circuit so that the printed circuit is clamped between the ceramic and counterweight thereof. The printed circuit includes conductors for connection to electrodes of the respective ceramic for individual control of the elementary transducers. The weight of each element of the elementary transducer is set to minimize cross-talk between channels.

Acoustic antenna having integrated printed circuits

An acoustic wave transducer includes at least one electroacoustic motor, a horn having an inner wall and an outer wall, a counterweight, and a hollow housing having an inner wall and an outer wall and at least one acoustic opening. The electroacoustic motor is connected to the horn and to the counterweight along an axis, and the electroacoustic motor is capable of exciting the horn at about at least one resonance frequency. The housing is connected to the counterweight and surrounds the motor and the horn, the outer wall of the horn being arranged opposite an acoustic opening of the housing, and the space between the inner wall of the housing and the inner wall of the horn defines a cavity that contains a fluid. The transducer includes acoustic attenuation elements connected to the outer wall of the housing in order to attenuate the emission and/or reception acoustic waves at the frequency at least in a direction transverse to the emission/reception axis. A sonar antenna that includes at least one transducer is also described.

Acoustic wave transducer and sonar antenna with improved directivity

A Bragg grating fiber hydrophone, includes a fluid chamber and an optical fiber in which a Bragg grating is integrated, the optical fiber passing through the fluid chamber along a longitudinal axis such that the Bragg grating is positioned inside the latter. The fluid chamber is filled with a compressible fluid and is defined by a casing including two ends connected to the optical fiber. The casing includes at least one portion formed by an extensible and compressible tube extending along the longitudinal axis. The portion formed by an extensible and compressible tube includes an outer end coinciding with one of the two casing ends and can be longitudinally deformed by a difference in the pressures applied on the walls thereof, which results in a variation of the length of the optical fiber as measured by a variation in the wavelength of a luminous flux extracted from the optical fiber.

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Marseilles, France

Frederic Mosca