Electric field intensity variation in the vicinity of a perfectly conducting conical probe: Application to near-field microscopy

A vibrating metallic conical probe has been used in near-field microscopic measurements to obtain optical resolutions much smaller than the wavelength. Numerical simulations of these complex problems have drawn most of the attention in the past. We propose here an analytical expression for the electric field intensity in the near region of a probe situated above the surface of a semi-infinite dielectric medium. It is given as a function of the observation point location, with the cone aperture, the dielectric medium permittivity, and the characteristics of the incident plane wave as parameters.