Biophysics

Aperture-free near-field microscopy (s-SNOM)

February 6, 2011.

Lecturer

ANTONIJA CVITKOVIĆ & NENAD OCELIĆ
Neaspec GmbH, Martinsried (Munich), Germany

Date and time

Monday, April 18, 2011, at 3:00 PM

Location

Lecture hall in the Mladen Paić building, Institute of Physics, Bijenička cesta 46, Zagreb

Abstract

The spatial resolution of conventional optical microscopes is limited by diffraction to approximately half the wavelength of light. To overcome this limitation, apertureless near-field scanning optical microscopy – s-SNOM – has been developed. Instead of lenses, s-SNOM uses very sharp metallized probes onto which a laser beam is focused. This creates a nanofocus at the tip of the probe, which locally interacts with the sample. Depending on the optical properties of the sample, such near-field interaction modifies the amplitude and phase of the light scattered by the probe. By detecting the scattered light and scanning the sample, the s-SNOM device simultaneously forms an optical image and a topographic profile of the sample. The optical resolution is determined by the radius of curvature of the probe tip and currently reaches 10-20 nm. It is particularly interesting that the spatial resolution in s-SNOM does not depend on the wavelength of light, so the same resolution is achieved in the visible part of the spectrum, as well as with infrared and THz waves.

Combining s-SNOM and laser sources in the desired part of the spectrum results in an analytical device that can non-destructively examine the chemical, structural and electrical properties of samples on the nanometer scale. Based on many years of scientific research and technical development in the field of near-field microscopy, Neaspec GmbH has produced the first commercial s-SNOM device, thereby creating the basis for the widespread application of this advanced method in various branches of research, including nanophotonics, materials characterization and semiconductor technology.

*Joint seminar of the Institute of Physics, Department of Physics, Faculty of Science and the Croatian Biophysical Society
IF seminar leaders Berislav Horvatić and Ivica Živković
Head of the seminar FO PMF Hrvoje Buljan

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