A side-view photograph (a) and a schematic representation (b) of the nPS with STM tip assembly installed. It comprises three aluminum bars and four cylindrical piezoelectric tubes. The labels in (b) correspond to (1) one of the four piezotubes, (2) tip assembly (see later), (3) wire connectors, and (4) one of the three ruby feet.
Top (a) and side (b) views detailing the piezotube and wiring layout. With the electrodes wired in parallel, and with appropriate signal summing, the number of control wires is reduced to four. In order to achieve displacement in the direction with electrodes wired in parallel, the piezotubes on each side of the center piece were oppositely polarized (b). Fine and coarse movements are performed using the same actuators.
Controlling the motion of the positioning stage in the and directions. For motion in the direction (a), sawtooth waveforms of equal magnitude and opposite polarity are applied to the side electrodes, displacing the stage by in each cycle. For motion in the direction (b), a sawtooth waveform is applied equally to all electrodes, displacing the stage by in each cycle.
Speed and step size for the nPS in the direction under various conditions. (a) and (b) show the speed and step size, respectively, as the applied voltage was varied at a frequency of 2.5 kHz. (c) and (d) show the speed and step size, respectively, as the frequency was varied at an applied voltage of 105 V.
The measured nPS resonance spectrum suggests that the vertical bending mode is at 13.6 kHz, and the horizontal bending mode is at 15.1 kHz. The rotational or torsional mode for the center brace rotating about the long axis of the nPS is 21.1 kHz.
Schematics of the modes of vibration for the nPS. (a) is the vertical bending mode , (b) is the horizontal bending mode , and (c) is the torsional mode . Dark lines represent the deformed shape, lighter gray lines represent the undeformed shape, and the crosses indicate the positions of the feet.
Comparison of the nPS vibrational spectrum with the standard and the stiffened beetle-type microscopes.
A simplified representation of the central piece of the nPS consisting of two rods and one rectangular block.
Estimated and measured modes of the nPS.
Control signals required for full STM functionality. The sector labels are as indicated in Fig. 2.
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