Although the role of the periodic errors of optical heterodyne interferometers in displacement measurements is fairly well understood, their influence on the calibration of other types of displacement sensors do not seem to be studied as extensively. We have performed a careful analysis of the role of these errors on the calibration of a capacitance displacement sensor, which is integrated in a linear piezoelectric transducer for nanometrology applications, over displacement ranges in the sub micrometer range. Assuming a linear dependence of the output voltage of the capacitance displacement sensor on the displacement it was found analytically that periodic the interferometer errors lead to a decaying oscillation of the sensor sensitivity as the displacement range used in the calibration increases. For use of a double path interferometer with a polarization mixing amplitude of 0.5 nm and a polarization mixing wavelength of 79 nm deviations of sensor sensitivity of 0.3% for a range of 0.2 mm and 0.029% for a range of 1 mm were estimated. The pronounced oscillations of the sensor's sensitivity over very small displacement ranges as predicted by the theoretical description were verified experimentally. An agreement within the experimentally observed spread was obtained.
Citation: Measurement Science & Technology
Issue: No. 11
Pub Type: Journals
calibration, capacitance displacement sensor, error analysis, interferometry, nanometrology