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
COMPACT STAND-ALONE ATOMIC-FORCE MICROSCOPE
VANDERWERF KO, PUTMAN CAJ, DEGROOTH BG, SEGERINK FB, SCHIPPER EH, VANHULST NF, GREVE J
REVIEW OF SCIENTIFIC INSTRUMENTS
vol 64 issue 10: p2892-p2897 OCT 1993
A stand-alone atomic force microscope (AFM) featuring large scan, friction measurement, atomic resolution, and liquid operation, has been developed. Cantilever displacements are measured using the optical beam deflection method. The laser diode and focusing lens are positioned inside the piezo tube and the cantilever at the end of the piezo tube. Because the laser beam stays on the cantilever during scanning, the scan range is solely determined by the characteristics of the piezo tube. In our case 30 x 30 x 9.5 mum3 (xyz). The optical beam deflection detection method allows simultaneous measurement of height displacements and torsion (induced by lateral forces) of the cantilever. AFM images of dried lymphocytes reveal features in the torsion images, which are only faintly visible in the normal height images. A new way of detecting the nonlinear behavior of the piezo tube is described. With this information the piezo scan is linearized. The nonlinearity in a 30-mum scan is reduced from 40% to about 1%, as is illustrated with images of a compact disk. The stand-alone AFM can be combined with a (confocal) inverted microscope, yielding a versatile setup for biological applications.