SUBNANOMETER BEHAVIOR OF A CAPACITIVE FEEDBACK, PIEZOELECTRIC DISPLACEMENT ACTUATOR

This paper presents the calibration of piezoelectrically actuated capacitance micrometers for use as a transfer standard of nanometer level precision using x-ray interferometry. Because of the interferometer's extreme sensitivity to twisting moments, there is a pressing need for high-quality transfer systems to widen its range of applicability. Two promising candidates for this are piezoelectric actuators controlled by internal capacitive sensors and parallel-plate capacitive micrometry. Both are investigated to determine useful precision for the discrimination and traceability over the range 1-20 nm. It is shown that systems of high mechanical stability can readily be produced. They offer at the very worst traceable accuracy of a few tenths of a nanometer, with, in the case of the gauge, a wide bandwidth of greater than 1 kHz. It is argued that existing technologies can provide calibrators working at relatively rapid speeds with uncertainties better than around 20 pm over usefully large ranges, presently 15-mu-m