Analysis of the measured signals in apertureless near-field optical microscopy.
We present an analytical model able to explain the optical signal recorded during our experimental approach curves in the infrared at a wavelength lambda=10.6 microm, with a home-made apertureless near-field scanning optical microscope ANSOM. This model uses classical electrodynamics to calculate the scattering cross section of the oscillating tip, considered as a dipole, and its dielectric image in the sample as a function of the tip-sample separation from the near-field to the far-field regime. The dipoles are placed in a non-uniform electric field because of the standing wave arising from the interference between the incident and the specular laser beams. We also added a background field coming from a scatterer on the surface in order to account for zeroing of the optical signal for particular tip-sample separation and interference patterns.
Formanek
F
F
Laboratoire d'Optique Physique, CNRS UPR A0005, Ecole Supérieure de Physique et de Chimie Industrielles, 10 rue Vauquelin, 75005 Paris, France. formanek@optique.espci.fr
De Wilde
Y
Y
Aigouy
L
L