Method and apparatus for rapid automatic engagement of a probe

Abstract

A method and apparatus of engaging a probe with a sample surface including automatically reducing the spacing between a probe of a probe based instrument and a sample from an initial separation to one in which the probe is positioned for obtaining a sample surface measurement in less than ten seconds without damaging either the probe or the sample. The method includes oscillating the probe, measuring at least one parameter of probe oscillation and then engaging the probe and the sample by generally continuously controlling the reducing step based on the measuring step to reduce the separation from an initial separation to an engage position. In addition to feeding back directly on the tip-sample interaction, a direct communication line is provided between the processor used to generate control signals that govern the engage and a conventional motion controller. In an alternative, a coarse positioning actuator and a fine positioning actuator in which the control of both is coordinated under feedback to place the probe in the engaged position, and wherein the close approach phase of the algorithm is controlled by a dedicated real time controller.