Controlling engagement of a scanning microscope probe with a segmented piezoelectric actuator

摘要

A scanning probe microscope includes a segmented piezoelectric actuator having a course segment and a fine segment, the outputs of which are combined to determine the movement of a distal end of the actuator, to which the probe is mechanically coupled. Movement of the probe tip, or a change in the level of its engagement with a sample surface is sensed by a detector, which generates a feedback signal. A correction signal, which is used to determine how the actuator should be moved to maintain a constant level of such engagement, is generated in a comparison circuit, which compares the feedback signal with a control signal. The correction signal is used to drive the fine segment of the actuator, while an integral of the correction signal is used to drive the coarse segment.