Limits to Mechanical Positioning and Displacement Measurements

Abstract

An essential requirement for any type of machine designed to shape or structure matter is the ability to move a forming tool or probe in an accurate, prescribed path throughout a workspace. Since the advent of the scanning tunneling microscope, we have been evolving rapidly in our capabilities to perform this function from machine-controlled cutting edges, to cutting with lasers and ions, to e-beam lithography, to recent demonstrations of controllably positioning individual atoms on a suitable substrate with STM tips. Any of these approaches requires that the probe or probes be moved and located in the workspace with a positional accuracy significantly smaller than the dimensions of the smallest feature being fabricated, and that the positioning be accomplished within a time scale to make the fabrication process practical.