High-resolution and high-power ultrasound method and device, for submarine exploration

An acoustic echographic method for underwater exploration, making use of the bubble-implosion effect, characterized in that it comprises the following steps:

• the realization of a parabolic transmitter, which is immersed in water and is open at its base, said transmitter having a thickness sufficient to prevent energy dispersions through its walls and presenting a predetermined focal length, the latter being selected to be sufficiently long so that the expansion of the bubble generated by the electric discharge occurring between two electrodes that are symmetrically arranged with respect to the focus is not hindered by the walls of the paraboloid formed by the transmitter;
• and wherein said electrodes are adjustable in the direction of the line that joins them, to allow to increase or decrease their reciprocal distance;
• the realization of a parabolic receiver, said receiver being open at its base, being immersed in water, and having a pressure sensor arranged substantially at the focus of the receiver;
• the connection of said transmitter to an electronic unit, having a function of control and energy supply, said electronic unit supplying electrostatic energy to said electrodes and transmitting an electric trigger signal to means of the receiver;
• the connection of said receiver to data processing and display means, for obtaining diagrams of the type of an oscillogram relating to received signals, and/or for obtaining acoustic images of these received signals;
• and a last step, in which, given a certain value of the electrostatic energy to be supplied to the electrodes, and given a certain degree of water salinity, the distance between said two electrodes is adjusted so that a maximum delay time is obtained between the occurrence of the breakdown electric discharge and a signal due to bubble implosion of the bubble formed during the same discharge, said maximum delay time of the bubble implosion signal being unequivocally correlated to the maximum acoustic efficiency value, given by the ratio between the electrostatic energy and the acoustic energy of the bubble implosion signal, and wherein, under these circumstances, the amplitude of the primary signal directly generated by the breakdown discharge is minimal or negligible.