Working principle of a tuning fork and its application in scanning probe microscopes
| Autor: | 柯文清 |
|---|---|
| Rok vydání: | 2003 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 91 This thesis presents a study on the working principle of tuning-fork-based shear force feedback devices frequently used in a scanning probe microscope. Resonant frequency of the tuning fork varies since non-contact interaction force acts on the probe as its tip becomes very close to a sample. Variation of the vibrating amplitude at the inherent resonant frequency is often used as an index to adjust the tip-sample distance within optical near-field range. The shear force feedback device is made of a commercial quartz tuning fork glued together with an optic probe of 50 nm aperture along one of the fork arms. The fork arm is modeled as an Euler beam that vibrates laterally and subjects to an axial force. The resonant frequency shifts due to geometric stiffness change caused by the axial interaction force. Combined with the tip force-distance formula presented by Argento and French, this study establishes a useful relation between the resonant frequency shift and the tip force. It is also successfully used to measure the interaction force between an optic probe and a silicon wafer. A shear force feedback scanning probe microscope was further developed during this research by a LabVIEW program integrating a lock-in amplifier, function generator, DSP-based PI controller through a GPIB interface. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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