Theoretical principles of near-field optical microscopies and spectroscopies

This paper deals with the principles of detection of optical signals near a surface in a manner permitting the mapping of the distribution of the fiel ds close to various kinds of illuminated samples. We begin with a discussio n of the main physical properties of the optical fields near a surface in t he absence of any probe tip. This mainly concerns phenomena involving evane scent waves for which the local decay lengths are governed not only by the sizes but also by the intrinsic properties of the surface structures. The i nterpretation of the detection process is reviewed on the basis of a discus sion about the possibility of establishing direct comparisons between exper imental images and the solutions of Maxwell equations or the electromagneti c local density of states. (C) 2000 American Institute of Physics. [S0021-9 606(00)70516-2].