It has been demonstrated by Gorceix and Indelicato and others that the effective potentials for the interaction between the electrons, derived in the Feynman and Coulomb gauges, respectively, lead to different results, when applied in a many-body procedure, even when the orbitals are generated in a local potential. This apparent gauge dependence is due to the fact that the standard many-body procedures include only the reducible part of the multiphoton exchange, while the irreducible part does contribute to leading relativistic order in the Feynman gauge but not in the Coulomb gauge. It is shown explicitly that when the irreducible part of the two-photon exchange (crossing photons) is taken into account, this gauge dependence is removed to leading relativistic order. The situation is expected to be the same in higher orders.

No abstract

The voice coil motor nanoscanner has the advantages of large working range, easy control, and low cost compared to the conventional lead zirconate titanate driven nanoscanner. However, it has a small damping problem which causes mechanical vibration. The mechanical vibration reduces the accuracy as well as servobandwidth, which deteoriates the atomic force microscopy (AFM) image of the samples. In order to solve the vibration problem, the loop shaping technique [for vertical (z)] and input prefilter [for lateral (xy)] are applied. Experimental results of the proposed techniques are presented for vertical (z) and lateral (xy) scanner. Finally, the AFM images are provided to investigate its effect.

No abstract

Many information storage devices have been introduced and developed in recent years. The trend for these devices is toward high capacity, compact size, low power consumption, reliability, and removability for data interchange with other devices. In addressing these trends, the near-field scanning microscope (NSOM) technique is in the spotlight as the next generation device. In order for a near-field device to be successfully implemented in a system, a slider and suspension must be introduced as actuating mechanisms. Consequently, a suitable slider and suspension needed to be designed. The optical slider should be designed considering near-field optics with the probe structure. The suspension should function generally to support slider performance and track servo capacity in hard disk drives (HDDs). Moreover, the suspension for an optical slider must meet optical requirements, and is also required to satisfy criteria for shock performance in the mobility of the actuator. In this study, the optical slider and the suspension for a near-field probe array are designed and analyzed.