摘要 |
An apparatus for measuring distance between two interfaces comprises a first electrically conductive planar member defining the first of the two interfaces, a second electrically conductive planar member defining the second of the two interfaces, an alternating electrical signal generator supplying an input alternating electrical signal to the first electrically conductive planar member through a first electrical conductor having a high value of ohmic resistance, and a phase difference measuring device measuring a phase angle difference between a first output alternating electrical signal taken off from one extremity of the second electrically conductive planar member through a second electrical conductor having a high value of ohmic resistance and a second output alternating electrical signal taken off from the other extremity of the second electrically conductive planar member or from the alternating electrical signal generator; wherein the distance between the two interfaces is determined as a function of the phase angle difference between the first and second output alternating electrical signals.
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