Development of a multi-functional multi-probe atomic force microscope system with optical beam deflection method

High-speed multiparametric imaging through off-resonance tapping AFM with active probe

Off-resonance tapping (ORT) mode of atomic force microscopy (AFM), based on force-distance curve, is widely concerned due to its advantages of weak tip-sample interaction and concurrent quantitative property mapping. However, the ORT-AFM still has the disadvantage of slow scan speed caused by low modulation frequency. In this paper, we overcome this disadvantage by introducing active probe method. With active probe, the cantilever was directly actuated with the induced strain after applying voltage in the piezoceramic film. In this way, the modulation frequency could be increased to more than an order of magnitude faster than that of traditional ORT, thus improving the scan rate. We demonstrated high-speed multiparametric imaging with the active probe method in ORT-AFM.

Thin head atomic force microscope for integration with optical microscope

We present a novel thin head atomic force microscope (AFM) that can be easily integrated with an upright optical microscope (OM). The optical beam detection unit in the AFM used an obliquely incident laser beam onto the cantilever, reducing the AFM head's effective thickness to 7.3 mm. That allows an open space above the cantilever probe to accommodate the objective lens up to 0.6 numerical aperture (N.A.) without obstruction. A multi-function digital controller was developed to control the AFM and reserved interfaces to communicate with the OM. To assess the performance of the developed AFM, we first measured the noise level and bandwidths of the AFM system. Then, the imaging quality of the AFM was evaluated by both calibration grids and two-dimensional materials. Finally, the thin head AFM was integrated into a homemade white light interferometer as a demonstration of combined use with an advanced optical system. The experimental results demonstrated that our developed AFM is suitable for integration under upright OM and brings AFM high-resolution advantages to the existing OM system.