Near-field microscope probes utilizing surface plasmon polaritons

The near-field microscope is characterized by its super-resolution capabili ty. It exceeds the classical limit of spatial resolution of the light micro scope due to the wave nature of photons or the diffraction of light. In thi s chapter, a general review of the methods for super-resolution in imaging optics is given, and how nearfield optics enables the super-resolution is e xplained using the Ewald sphere. The common and distinctive mechanisms and functions of different near-field probes are compared using eight configura tions including the probes associated with surface plasmon polaritons. The imaging mechanism of the near-field optical micrscope is different from the classical light microscope; the light intensity is detected as a resul t of strong electromagnetic interaction between the probe and the sample st ructure in the near-field via evanescent photons, so that the system is not a linear passive one but a more complex one. Since this microscope uses ph otons to see the structure, the energy or wavelength range in the optical s pectrum is an important issue to be discussed. This chapter describes these topics as an introduction to the following chapters.