Study of shear force technique for near-field microscopy with an uncoated fiber tip

The shear force technique, which is based on the detection of intensity variations in the diffracted light from a laser beam incident on the resonantly vibrating fiber tip, is considered. Two simple mechanical models are used for estimating the magnitude of the forces involved in the tip-surface interaction. A theoretical model describing the optical detection part of the shear force technique is developed for uncoated fiber tips. It is shown that when using an optimum configuration of the detection system, a tip vibration amplitude of 1 nm can result in up to 50 nW of the detected optical signal for the laser beam power of 5 mW. The calculated results are compared with experimental data.