Field Emission Ultramicrometer

Abstract

A simple, contact free, ultrasensitive distance and displacement measuring instrument has been investigated. Experiments demonstrate that the instrument is capable of operating at spacings as small as a few hundred angstroms. Calculations indicate that distances of 10⁻³ to 10⁻⁶ cm and less can be reproduced to within about one part in 10⁵. With suitable calibration, distance measurements in the 10⁻³ to 10⁻⁶ cm range can be expected to have accuracies limited only by available calibration techniques. The instrument would be most useful as a null or differential distance measuring device. It has the unusual property that resolution improves over several orders of magnitude as the null or measurement point is approached. Since the instrument contains no optical or mechanical lever systems, or delicately balanced bridges, it has inherent long term stability. Proposed applications include: (1) measurement of ball and hole diameters (contact free), (2) differential thermal expansion cell, (3) mechanical vibration sensor, (4) surface profile delineator (contact free), and (5) surface contour delineator (contact free).