Ultra precise 2-dimensional atomic tracking control for atom craft

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Since ultra precision engineering, e.g. nanotechnology, has progressed rapidly, a new positioning method with sub-nanometer resolution is required. The lattice spacing of approximately 0.2 nm for some regular crystalline lattice is uniform and stable over a long range, if the crystal is stress free. The scanning tunneling microscope (STM) has high performance to obtain an atomic image of a crystalline surface. Therefore, such crystelline lattice can be used as a positioning reference with sub-nanometer resolution by combining the crystal and a STM. We have proposed an atomic tracking control of the STM tip by referring atomic apex points and arrays on crystalline surface. In this research, a stabilization method for the atomic tracking control against the outer disturbances has been developed. The following results were obtained using the fund.(1) An ultra precise stage with fine straight motion was developed. The straightness of 0.2 arc second, the resonance frequency of 2 kHz and sca … More nning range of 10 micrometer were evaluated, respectively. An atomic image was obtained easily using the stage and a STM head.(2) The noises on the tunneling current of the STM against the outer disturbances were analyzed and divided into the following three parts; (A) the sound noise in air, (B) the thermal drift between the STM tip and the sample and (C) the vibration noise from the floor. The part (C) can be removed by enhancement of the stiffness of the STM instrument and by use of the anti-vibration table. The amplitude and frequency for the part (A) were relatively small and high, respectively. However, the amplitude change and frequency for the part (B) were relatively large and slow, respectively.(3) The two-stages PI controller was implemented for the stabilization of the atomic tracking control. Each stage PI controller was adjusted for compensation of the disturbance (A) or (B), respectively, and then they were combined with. Both the disturbance (A) and (B) were compensated well with the two-stage PI controller. Less