Apertureless scanning near-field second-harmonic microscopy

We propose a new type of apertureless scanning near-field optical microscop e based on detection of the second-harmonic signal induced by or generated at a probe tip. We discuss the image formation in this technique and presen t numerical studies for different experimental circumstances. In two extrem e cases this method is shown to be the nonlinear analogue of apertureless s canning near-field optical microscopy based on local nanoscopic fluorescenc e or scattering. (C) 2000 Published by Elsevier Science B.V. All rights res erved.