Reduction of cross-coupling between X-Y axes of piezoelectric scanner stage of atomic force microscope for faster scanning

Abstract

In this paper we describe the cross-coupling effect between X-Y axes of piezoelectric tube (PZT) scanner used in an atomic force microscope (AFM). During raster scanning X-Y axes induced cross-coupling effect in the lateral positioning of the scanner stage of the AFM and as a result, it produces blurred or distorted images. To address this effect, an LQG controller is designed and implemented on AFM which minimizes the cross-coupling effect between the axes mainly at the resonance frequency of the scanner tube. The proposed controller has an integral action with the error signal which makes it possible to track the reference signal and a significant damping of the resonant modes of the PZT in the X and Y axes. This controller compensates the cross-coupling between X-Y axes dynamics of the AFM system, reducing the artifacts instigating by the system dynamic behavior at high scan rates. The closed-loop frequency responses for both the axes have achieved high bandwidth. Consequently, scanned results are evaluated as a better one than the open-loop of the AFM.