ACOUSTIC THICKNESS MEASUREMENTS USING GAS AS A COUPLING MEDIUM

摘要

An acoustic apparatus adapted to operate in a gas filled space for making a non-contact thickness measurement of an object to be measured or for making a non-contact characterisation of a medium located on the opposite side of the object. The apparatus comprises an electro acoustic transceiver to output an acoustic signal towards the object to be measured and receive an acoustic response signal, and a signal processor to process the response signal and to determine the thickness of the object. The transducer has a transducer-to-gas acoustic interface, and is adapted to emit an acoustic broad band pulse towards the object and to receive an acoustic resonance response signal. The signal processor determines the thickness of the object to be measured or makes a characterisation of a medium located on the opposite side of the object using a fast Fourier transformation (FFT) of the resonance response signal above a predetermined signal to noise level.