Utilisation d’une source laser pulsée à haute energie comme source acoustique large bande en milieu liquide

Abstract

In a second step, parameters affecting the efficiency of the opto-acoustic conversion were investigated. In order to get better laser propagation conditions in water the laser wavelength was changed from 800nm to 400nm. This was achieved by using a KDP crystal (second harmonic generation). The influence of optical pulse duration and total laser pulse energy on the level of the received acoustical signals were successively investigated. In this experiment three hydrophones were used, covering all together the frequency band [0-15MHz]. Finally, some tests of sound source generation in a saline solution (35g/l NaCl) were made in order to predict what would be the source level in a real sea experiment.