Xing ZHU, Gui-Song HUANG, He-Tian ZHOU, Xiao YANG, Zhe WANG, Yong LING, Yuan-Dong DAI and Zi-Zhao GAN

Department of Physics and State Key Laboratory for Mesoscopic Physics, Peking University, Beijing, 100871, China

(Received August 17, 1996; Accepted December 6, 1996)

We have developed a novel sample-tip regulation for a near-field optical microscope: an ultrasonic resonance regulation method. The regulation range is from 0 to 50 nm. It shows not only stability, simplicity in construction, but also versatility in vacuum, magnetic field, and low temperature environments. The main advantage of this technique is that it is a non-optical detecting scheme, which is very important for near-field spectroscopy. Such construction can also be used as a force microscope to study the topography of insulating samples. The laser light induced force interaction in the near-field range has been observed for the first time, showing that aided by laser radiation, the shear force between sample and tip can be changed depending on the type of sample. This can be interpreted as the light induced optical tip-sample interaction of light pressure effect. The van der Waals dispersion energy and the optical binding energy induced by laser beam between dielectric tip and samples play important role. The effect confirms a theoretical prediction. This new technique and phenomenon will add new aspects to near-field optics.

Key words : scanning near-field optical microscopy, ultrasonic regulation, shear force, laser induced force

*This paper was originally presented at the first Asia-Pacific Workshop on Near Field Optics, which was held on August 17 and 18, 1996 at Seoul Education and Culture Center, Seoul, Korea, organized by Condensed Matter Research Institute, Seoul National University.