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[摘要]：The bi-layer thin film measurement system uses the principle of frequency modulation for the detection of displacement. The measuring system utilizes a personal computer based system using the LabVIEW(R) graphical programming package that provides the features necessary for acquiring the sensor signal, analyzing it and displaying the results. The results from the acquisition were compared with previously developed amplitude and phase modulation based systems to show that the frequency modulation technique provides a robust and accurate solution to evaluate magnetostrictive materials and their application in magnetic sensors. The performance of the bi-layer thin film sensor was examined and its thermal stability, over the temperature range of up to 180 degrees C, was tested in an environmental chamber. The temperature rise does cause inductance change, but the sensor signal remains unaffected due to the nature of the frequency modulation method. Thus, having two materials, with different thermal coefficients of expansion in a bi-layer thin film sensor does not adversely influence the sensor signals. This creates a temperature independent sensor that is needed for applications where there are temperature variations. (C) 2007 Published by Elsevier B.V. |
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