Abstract: According to an embodiment of the invention, the device comprises a unique optical path and a movable means providing for the selective passage of a light beam respectively through a transparent cell (4) containing a substance to be studied, at least one reference filter (6). The light reflected successively by one and the other of said two components is selectively applied to three filters (F 1-F3) which filter three wavelenghts selected as a function of the substance to be analyzed. Three detectors (D1-D3) are used to measure the successive light intensities which have gone through each of the filters, and from the measures obtained, it is possible to determine a correction coefficient before calculating a characteristic of the substance contained in the transparent cell.

Abstract: A first embodiment of the invention includes a light source (1) lighting two parallel optical branches (b1, b2) controlled respectively by two optical shutters (4, 6), one comprising a transparent cell (3) containing a substance to be studied, and the other being used to divert the light from the source. The light coming successively from one and from the other branch is applied selectively to three color filters (F1-F3) filtering three wavelengths selected according to the substance to be studied. The successive luminous intensities which have crossed each of the filters are measured through three detectors (D1 to D3) and the measurings are combined by means of a control (0). Analogous measuring sequences may be achieved with an embodiment comprising three light sources and a single detector. The device can be used for determination of the pH value of a substance.

Abstract: A device for measuring the pressure difference between the two ends of at least one flexible tube connecting together the positions occupied by two elements. In a preferred embodiment, to a summing circuit are applied the signals delivered by two differential pressure sensors disposed respectively at the two positions and to which are applied the pressures prevailing in two flexible tubes, one containing a fluid of a density greater than that of air and the other containing air, these two tubes joining together the respective inputs of the two sensors. An accumulator maintains the static pressures prevailing in both tubes equal. The device is accurate and practically insensitive to temperature variations and accelerations.

Abstract: A method and device are provided for measuring the vertical movements of a floating object, for example, in the absence of a fixed reference point. Using a differential pressure sensor, the pressure difference is measured which prevails at a measurement position on the floating object, between the instantaneous atmospheric pressure and a reference pressure which is the atmospheric pressure prevailing in a container in communication with an element for damping the instantaneous pressure fluctuations, comprising a capillary tube. A regulation loop compensates more particularly for the temperature variations. By means of another loop, the influence of the very slow variations and of the local static pressure on the signal delivered by said sensor may also be corrected. Variations of altitude of 10 cm may for example be measured with said device.

Abstract: A process is provided for transmitting a signal, without material connection, through a conducting wall which may be a ship's hull, to external user apparatus.A current supplied by a generator and whose intensity is proportional to the amplitude of the signal to be transmitted is applied between two points on the hull. The magnetic field variations generated by the passage of the current are detected by a sensor on the other side of the hull and, suitably amplified, are used for controlling an apparatus.

Abstract: The position of a submerged object towed at great depth from a ship is determined, with respect to the ship, from measured values of the travel time of acoustic pulses between the ship and the object. These pulses are emitted at different locations of the ship and received at a point of the object. The values of the travel times of the pulses are measured and digitized on the object and transmitted by cable to the ship where they are processed, in combination with values representing the distances between the emission locations, to determine the coordinates of the object with respect to a system of axes associated with the ship.

Abstract: A device for recording data on a photosensitive recording support comprises a light beam transmitter, means for modulating the intensity of said light beam in relation with the data to be recorded, a fiber optic transducer with one circular end and one straight end, in operative relation with the modulating means at the circular end and with the recording support at the straight end and means for incrementally displacing said support relative to the transducer.

Abstract: This sonar system, placed on a vehicle such as a ship or a submarine, comprises transducer means for transmitting and receiving acoustic waves at two different frequencies, said reception means being adapted to generate echograms of the submerged surface from the received echoes of the transmitted pulses, the directivity diagram of said transducer means comprising a main transmission lobe whose axis is inclined with respect to a vertical line in a plane orthogonal to a first direction of displacement of the vehicle and a second transmission lobe oriented along a vertical line, means for determining the displacement velocity of the ship along said first direction, means for determining the water depth below the vehicle from the measured values of the propagation time of the waves transmitted along the direction of the secondary lobe and means for determining the displacement velocity of the vehicle in a direction orthogonal to the first one, by measuring the frequency of the acoustic waves received along a par

Abstract: Device for determining the relative position of at least one seismic streamer comprising acoustic pulse sensors, with respect to a seismic streamer comprising acoustic pulse transmitters, all of said streamers being towed behind a ship, comprising a telemetrical system for measuring the distance between pulse sensors and pulse transmitters by the determination of the travel time of pulses between different pulse transmitters and corresponding pulse sensors and a viewing system for displaying the so-measured distance.

Abstract: Acoustic wave transmitter-receiver comprising at least one pair of transducer assemblies arranged symmetrically with respect to a vertical axis, the transducers of each assembly being lined up with a regular spacing such that the projection length thereof on the vertical axis is equal to a whole number of wave lengths of the transmitted acoustic waves, means for generating transmission signals and means for transmitting the latter, in phase opposition, to the two transducer assemblies of said pair.

Abstract: Method and apparatus for determining the distance travelled by a vehicle with respect to a reference surface from the frequency shift between the frequency of signals transmitted from the vehicle and the frequency of echo-signals reflected on said surface in which the transmitted signals consist of a series of pulses of variable recurrence period whose duration is shorter than the propagation time interval of said signals from the transmission point to the reception point of the echo-signal and in which the frequency of the signals constituting said pulses is variable during the period of each pulse.

Abstract: Method for determining the shape of an underground cavity and the location of the interface between two media contained therein by making use of a sonic sonde comprising performing, for each position of the sonde, a series of measurements of the time interval between the transmission of an ultrasonic wave from the sonde and the reception of the corresponding echo after reflection on the wall of the cavity, the selection from said measurements of one of those indicating substantially identical time intervals so as to eliminate the false echos and the determination of the average value of the propagation time of said selected echo for each different location of the sonde and for each direction of the transmitted waves.