Abstract: An acoustic polarimeter is provided for measuring the acoustic birefringence of a plate with parallel faces.The plate to be measured is fixed to one face of an acoustically isotropic body and to the other face are fixed transducers having their linear transfer axis at 90.degree. from each other transmitting waves at pulsation .omega. modulated respectively by cos .OMEGA.t and sin .OMEGA.t. After reflection from the rear face of the sample, the signals X.sub.1 and Y.sub.1 received by the transducers are processed in processing circuits. The signals x.sub.1 and y.sub.1 are multiplied by a signal cos (.omega.t+.phi.) supplied by a phase-shifter controlled by a signal S.sub.1. After filtering, signals X and Y are obtained which are used for generating two signals A and B. A microprocessor receiving the amplitudes of these signals A and B controls the phase-shifter and supplies the birefringence angle .phi.. The direction of the first axis is obtained by synchronous detection of signal A.sub.1 by sin 2 .OMEGA.t.

Abstract: An acoustic polarimeter for measuring the anisotropy of a sample comprises an electroacoustic transducer which transmits a high-frequency transverse acoustic wave and is fixed on a birefringent measuring plate. The acoustic wave is received by a second transducer and this latter is sensitive to the component of the wave which is parallel to the transmitted wave. Transmission devices are provided for delivering electrical signals which are frequency-modulated about a tunable mean frequency. The electrical signals applied to the second transducer are received on a zero indicator, thus permitting determination of the directions of the slow axis and fast axis of the sample as well as the angle of phase shift introduced by the sample.

Abstract: Batteries activated by immersion in the sea comprise a case containing battery elements separated by tightly sealed partitions. These elements are electrically connected in series.Tubes leading to the elements are used for filling and for discharging gases. These tubes are connected to first connecting tubes, coaxial to second connecting tubes issuing to the outside by means of openings.Application to long-life batteries for sonic buoys which can be dropped from an aircraft.

Abstract: The device comprises an elongated acoustic wave translating isotropic body and a pair of transducers applied over one of the two parallel end faces thereof. Said transducers are arranged with relatively crossed axes of linear transversal polarization. The other end face of the isotrope body is intended to be applied to a sample or a structure made of an acoustically active substance presenting anisotropy, either intrinsic or induced, with respect to acoustical polarization. The length of the isotropic body is such that when the transducers are both simultaneously driven by pulsed high frequency voltages which are modulated in respective phase quadrature by a low frequency oscillation, the two transversal acoustic waves propagated through the body vectorially combine so that the opposite end face of the body is the subject of a constant amplitude acoustic wave which rotates at the speed of the pulsation of the low frequency.