Method for optically and remotely sensing subsurface water temperature

摘要

A method for remotely measuring an unknown temperature Ts of a transparent medium by comparison with the known temperature Tr of a transparent reference material consisting of the steps ofP Pcombining the outputs of a continuous-wave (CW) laser and a high intensity pulsed laser to form a combined laser output beam, wherein the high intensity pulse component of the output beam exceeds the intensity required to produce stimulated Brillouin scattering (SBS) in the transparent medium;PPsplitting the combined laser output beam into first and second sub-beams;PPamplifying the CW components of the first sub-beam to an intensity exceeding the intensity required to produce stimulated Brillouin scattering (SBS) in the reference material while simultaneously suppressing the pulse components in the first sub-beam;PPdirecting the first sub-beam with the amplified CW component into the reference material and thereby generating a CW phase-conjugate beam;PPdirecting the second sub-beam into the transparent medium and generating a pulsed phase- conjugate beam;PPmixing the CW and pulsed phase- conjugate beams in a photodetector and producing a difference frequency proportional to TS-Tr; andPPconverting this difference frequency into a value of Ts.