Superresolution of near-field optical microscopy defined from properties of confined electromagnetic waves

Abstract

The experimental resolution that is obtained with a near-field microscope by optical tunneling detection is far beyond the Rayleigh criterion. We discuss the principal physical characteristics of this superresolution. Three different examples are presented. They show that the resolution increases as the collector width and collector-to-object distance decrease. It is interesting to note that, in the near-field microscope, as in all local probe microscopes, the resolution cannot be defined from the characteristics of the microscope only. In all tunnel devices the detector cannot be separated from the object. The superresolution that can be obtained results from this fact. This paper also points out the importance ofevanescent waves in near-field optics and makes the connection between resolving power and evanescent fields.

A near infrared holographic glucose sensor

“…The incident light from the hologram or laser are both in a single polarized state, and thus the surface plasmon waves of the particles are selectively polarized and the excited waves depend on the characteristics of the nanoparticles such as aggregation. Moreover, based on diffraction theory, a particle illuminated with a propagating wave generates diffracted evanescent modes and conversely, based on the reciprocity theorem, a particle located in an evanescent field converts part of this field in to propagating waves (Vigoureux and Girard, 1992). Thereafter, laser ablation and/or the holographic replay may equally result in a change of the surface plasmon resonance and hence in light scattering of the nanoparticles.…”

Application of Fourier algorithm to Near Field Optical Images: Local Resolution Estimation

“…On [1]. They take into account either the tip size [22] or theoretical aspect of imaging [11,14,17,[23][24][25][26][27]. Some are developed around statistical processing of experimental data [28,29], or the setup cut-off frequency determination [18].…”

“…The resolution is often determined by examining the intensity curve [5] or the image Fourier spectrum in the case of periodic samples [7,8]. On the opposite, theoretical studies describe the image formation with simulated images [9][10][11][12][13][14]. In that context, the resolution in near field optics was studied [15].…”

Nonlinear Near Field Optics

“…As underlined in studies of the sub-Rayleigh resolution of the SNOM [12], one of the essential characteristics of near field microscopy is that the detector cannot be considered as being separated from the object . Thus resolution of the SNOM cannot be defined, from the knowledge of the detector only .…”

“…Another one is concerned with the confinement of the electromagnetic field (in the vicinity of nanometre scale objects) which is able to enhance nonlinear effects . As explained in [12], a characteristic of near field optics is that the detector can never be considered as separated from the object . Because of this, nonlinear effects occurring in the near field zone depend on the characteristics of the detector (size, shape, metallic or dielectric character, etc .)…”