1. Principle of the near-field microscope

To appreciate the originality of these new instruments and understand the source of their excellent resolution, we need to briefly review how a traditional microscope works.

In traditional microscopes (optical or electronic), a source of waves (or particles) illuminates an object. The diffracted radiation is then conveyed through optics to the detector (CCD, etc.), which produces a magnified image of the object. The distances between the source and the sample, and between the sample and the detector, are much greater than the wavelength λ of the radiation used.

The smallest distance that can be perceived in the image plane (the inverse of lateral resolution power) is of the order of λ; this theoretical limit is inherent in the phenomenon of radiation propagation through optical magnification systems and, in particular, in the phenomenon...