Application of atomic force microscopy to an encoder

Minute position measurement is needed in the field of precision engineering. We have proposed an encoder using the principle of the an atomic force microscopy (AFM), which is called the AFM encoder. Since the AFM realizes atomic scale resolution, an encoder having the atomic scale resolution will be realized. The AFM encoder is a multiple probe AFM. The deflections of AFM cantilevers are detected by a Michelson interferometer simultaneously. A line-focused red color semiconductor laser is used as a light source and a photodiode array is used as a detector. The periodicity of a crystal lattice, for example the highly oriented pyrolytic graphite, is used as the standard of displacement. The AFM cantilevers detect surface topography with atomic resolution and measure the displacement by using the detected signals. In this paper, two AFM cantilevers are used as the probes of the AFM encoder. An optical grating is used as a displacement standard and a pitch of the optical grating is 1.1 μm. Surface topography is obtained by two AFM cantilevers simultaneously