Method and device for measuring inside diameters using a laser interferometer and capacitance measurements

摘要

A method and device for measuring the distance between first and second positions on an inside surface of a metal part that includes locating a metal probe within the part, applying a voltage across the probe and part, measuring the capacitance between the probe and part, moving the probe toward the first position until a predetermined capacitance is measured, moving the probe toward the second position until the predetermined capacitance is measured, determining the distance travelled by the probe between the first and second positions, and adding to the determined distance a known value to compensate for the width of the probe and the distance between the probe and part when the predetermined capacitance is measured.