Position measurement using atomic force microscopy

Abstract

Minute position measurement is needed in the field of precision engineering. We have proposed an encoder using the principle of atomic force microscopy (AFM), which is called the AFM encoder. Since the AFM is able to observe an atom, the AFM encoder will realize the atomic scale resolution. The multiple probes of the AFM encoder are two AFM cantilevers. A Michelson interferometer is used for detecting the deflection of the AFM cantilevers. Since a line-focused laser beam is used as a light source and a photodiode array is used as a detector, the deflections of several AFM cantilevers are measured simultaneously. The detected signals are the signals of the AFM encoder. The periodicity of the sample is the standard of the position measurement. An optical grating whose periodicity is 1.1 /spl mu/m is used as a standard of the displacement. The displacement of the sample is measured by the signal of the AFM encoder. In our previous experiment, the resolution was about 30 nm. The experimental setup is improved and we obtain the resolution of less than 1 nm.