Submerged Objects Detecting in the Focusing Regime of Stimulated Brillouin Scattering

A method to detecting Submerged Objects by using the effective interaction length of Stimulated Brillouin Scattering (SBS) in the focusing regime is presented in this paper. Relationship of reflected energy dependent on the location of the object in Stimulated Brillouin Scattering cell is introduced, which is used to give the location of Stokes signal disappearing theoretically. We experimentally study Submerged Objects detecting measurements when the detected object is present in three different place, i.e., in front of the focus, just in the place of the focus and the behind of the focus. The delay time of the echo signal to pump signal can give the location of Submerged Object. Using input laser with 532nm nanosecond pulse generated by Q-switched Nd:YAG laser, experimental results show when object is placed in front of focus the measurement error is the lest and the error was less than 4% within 188cm water cell.