Patent ID: 7404671

Claim:
A method for measuring temperature at a remote location of a structure that includes a first surface on one side of the structure and a second surface on another side of the structure, where a perpendicular distance between the first and second surfaces defines a thickness of the structure, the method comprising: providing at a source location an acoustic source transducer disposed on or near the first surface of the structure and separated from the remote location; providing at a receiver location an acoustic receiver transducer disposed on or near the first surface of the structure and separated from the remote location; propagating acoustic radiation from the source transducer to the receiver transducer through a medium along a path that passes through or near the remote location; measuring multiple times an acoustic delay associated with propagating the acoustic radiation along the path; integrating the multiple measured acoustic delays to obtain an integrated acoustic delay; measuring a change in the integrated acoustic delay as a function of time; and processing the measured change in the integrated acoustic delay using a thermal-acoustic model relating a non-uniform temperature distribution along the path with a non-uniform distribution of acoustic propagation velocity along the path to determine the change in the remote location temperature.