Biomolecules and nanostructures
The Optical Sciences group studies the interaction of light and matter at the nanoscale.
We do this by exploring ways to shape light and its environment. It's what we call
active and passive control. Our current focus is on the interaction of light with
biomolecules and nanostructures. We are part of Twente
University's Department of Science and Technology and member of the
Dynamic behavior of tuning fork shear-force feedback(full pdf)
Ruiter AGT, Veerman JA, vanderWerf KO, vanHulst NF
APPLIED PHYSICS LETTERS
vol 71 issue 1: p28-p30 JUL 7 1997
The dynamics of a tuning fork shear-force feedback system, used in a near-field scanning optical microscope, have been investigated, Experiments, measuring amplitude and phase of the tuning fork oscillation as a function of driving frequency and tip-sample distance, reveal that the resonance frequency of the tuning fork changes upon approaching the sample. Either amplitude or phase of the tuning fork can be used as distance control parameter in the feedback system. Using amplitude a second-order behavior is observed while with phase only a first-order behavior is observed, and confirmed by numerical calculations. This first-order behavior results in an improved stability of our feedback system, A sample consisting of DNA strands on mica was imaged which showed a height of the DNA of 1.4 nm. (C) 1997 American Institute of Physics.