Development of XY scanner with minimized coupling motions for high-speed atomic force microscope

Abstract

The design and fabrication processes of a novel scanner with minimized coupling motions for a high-speed atomic force microscope (AFM) were addressed. An appropriate design modification was proposed through the analyses of the dynamic characteristics of existing linear motion stages using a dynamic analysis program, Recurdyn. Because the scanning speed of each direction may differ, the linear motion stage for a high-speed scanner was designed to have different resonance frequencies for the modes, with one dominant displacement in the desired directions. This objective was achieved by using one-direction flexure mechanisms for each direction and mounting one stage for fast motion on the other stage for slow motion. This unsymmetrical configuration separated the frequencies of two vibration modes with one dominant displacement in each desired direction, and hence suppressed the coupling between motions in two directions. A pair of actuators was used for each axis to decrease the crosstalk between the two motions and give a sufficient force to actuate the slow motion stage, which carried the fast motion stage. A lossy material, such as grease, was inserted into the flexure hinge to suppress vibration problems that occurred when using an input triangular waveform. With these design modifications and the vibration suppression method, a novel scanner with a scanning speed greater than 20 Hz is achieved.

Keywords

atomic force microscope / scanner / piezoelectric stack actuator / crosstalk / flexure hinge