Optical Sciences

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 MESA+ institute.
We participate in the EU-COST actions MP1102: Coherent Raman microscopy (MicroCor) and CM1202: Supramolecular photocatalytic water splitting (PERSPECT-H2O)

 

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.
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