A piezoelectric bimorph-based scanner operating in tip-scan mode for high speed atomic force microscope (AFM) is first presented. The free end of the bimorph is used for fixing an AFM cantilever probe and the other one is mounted on the AFM head. The sample is placed on the top of a piezoelectric tube scanner. High speed scan is performed with the bimorph that vibrates at the resonant frequency, while slow scanning is carried out by the tube scanner. The design and performance of the scanner is discussed and given in detailed. Combined with a commercially available data acquisition system, a high speed AFM has been built successfully. By real-time observing the deformation of the pores on the surface of a commercial piezoelectric lead zirconate titanate (PZT-5) ceramics under electric field, the dynamic imaging capability of the AFM is demonstrated. The results show that the notable advantage of the AFM is that dynamic process of the sample with large dimensions can be easily investigated. In addition, this design could provide a way to study a sample in real time under the given experimental condition, such as under an external electric field, on a heating stage, or in a liquid cell.

Resonance-type bimorph-based high-speed atomic force microscopy (HSAFM) capable of operating in the sample-scan and tip-scan modes is presented in this paper. The working principle of the high-speed scanner, the experimental setup, and the data collection system are described in detail. The main characteristic of the high-speed scanner is the use of a piezoelectric bimorph, where one of the piezoelectric layers is used to drive the bimorph beam to scan at a high speed and the other monitors the bimorph vibration. Image distortions due to the phase-lag and sinusoidal scanning are analyzed and simulated. The correction methods for the compensation of the phase-lag and nonlinear movement are proposed based on data shift and nonlinear mapping relations, respectively. The HSAFM imaging at the maximum rate of ~30 frames per second is demonstrated with our data collection and correction program. The image distortions caused by the phase-lag and sinusoidal scanning are effectively eliminated in real-time. This work would provide useful methods for the development of HSAFM and applications in the observation of dynamic processes at nanoscale.

The optical lever detection method has been widely used to detect the cantilever deflection in atomic force microscope (AFM) due to its simple mechanism and high sensitivity. The deflection detection of very small cantilever is a key and difficult issue in the development of a high-speed AFM. In this paper, a specially designed optical beam deflection detection system based on an aspheric lens is presented. The aspheric lens is fixed on an adjustable metal tube above the cantilever to focus the laser beam with a small spot. Two laser line beamsplitter cubes are installed symmetrically and oppositely over the aspheric lens with separately mounting a diode laser and a position sensitive detector (PSD) on two translation stages at the same height. The collimated laser beam is reflected down by one cube and focused by the aspheric lens at an off-centered position. The focused beam is then incident upon the cantilever and reflected back onto the opposite off-centered position. Change in the reflection angle caused by the cantilever deflection results in a parallel shift of the outgoing laser beam after the aspheric lens. The laser beam is finally reflected onto the PSD by the other cube. Experimental results show that the laser beam can be focused with a spot of less than 16 µm in diameter. With above system, the deflection detection of the small cantilever can be realized, which meets the requirement for the use in a high-speed AFM.