A phase-locked shear-force microscope for distance regulation in near-field optical microscopy
作者:
Walid A. Atia,
Christopher C. Davis,
期刊:
Applied Physics Letters
(AIP Available online 1997)
卷期:
Volume 70,
issue 4
页码: 405-407
ISSN:0003-6951
年代: 1997
DOI:10.1063/1.118318
出版商: AIP
数据来源: AIP
摘要:
A nonoptical phase-locked shear-force microscope utilizing a quartz crystal tuning fork acting as a voltage-controlled oscillator in a phase-locked loop has been implemented. A tapered optical fiber is rigidly mounted on one of the prongs of the fork to serve as both a shear-force pickup and a near-field optical probe. The crystal is driven at its resonance frequency through positive feedback of the monitored current through the crystal. This signal is used as the voltage-controlled oscillator in a phase-locked loop. The scheme allows for scan speeds far beyond the Q-limited amplitude sensor bandwidth and exhibits excellent sensitivity for a high-Q resonator. Furthermore, given the small vibration amplitude of the tip(<0.5 nm) and the distance over which it is reduced(>6 nm), it is unlikely that the tip is making direct contact with the sample surface as has been suggested for the optical shear-force detection scheme. ©1997 American Institute of Physics.
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