The influence of a focused polarized Gaussian beam on image formation was studied. We show that the position of the tip with reference to the center of the beam involves asymmetry in the intensity map. A comparison between <i>s</i> and <i>p</i> polarization can be made, owing to the definition of both a three-dimensional polarized Gaussian beam and a three-dimensional object. This result implies that the best way to scan a sample consists in moving it and not the tip; moreover, focusing the incident light to get a higher signal-to-noise ratio must be done carefully with respect to the sample period.
© 1999 Optical Society of America
(050.1950) Diffraction and gratings : Diffraction gratings
(180.5810) Microscopy : Scanning microscopy
(240.7040) Optics at surfaces : Tunneling
(260.6970) Physical optics : Total internal reflection
Fadi I. Baida, Dominique Barchiesi, and Daniel VanLabeke, "Near-field effects of focused illumination on periodic structures in scanning tunneling optical microscopy," Opt. Lett. 24, 1587-1589 (1999)