A perturbative diffraction theory of a multilayer system: applications to near-field optical microscopy SNOM and STOM

Near-field intensity distribution of waves scattered from slightly rough surfaces

The near fields of electromagnetic waves scattered from two-dimensional slightly rough surfaces are studied by using the stochastic functional approach. The correlation coefficient between the surface and the intensity of the scattered-wave field is investigated to estimate the fidelity of near-field intensity images. We show that the fidelity depends on both the polarization and the angle of incidence and that high fidelity can be obtained by a TM-polarized incident wave whose incident angle is not close to the critical angle of the total reflection.

Image resolution in reflection scanning near-field optical microscopy using shear-force feedback: characterization with a spline and Fourier spectrum

Scanning near-field optical microscopes (SNOM's) actually lead to nanometric lateral resolution. A combination with shear-force feedback is sometimes used to keep the SNOM tip at a constant force from the sample. However, resolutions in shear-force and optical data are different. An estimation of both resolutions is important for characterizing the capabilities of such systems. The basic principle of the measurement is to compare a spline-fitted logarithm of the power spectra calculated with the optical image with that of the shear force image in which resolution is determined a priori. Quantitative results are given in the case of periodic or untested sample and simulated data. Moreover the accuracy and the stability of the method are discussed.