Scanning near-field optical data contrast measurement: a tomographylike near-field reconstruction

A method for the reconstruction of near-field optical signals is proposed to produce a tomographylike map of the field above the nanostructures being studied. The data obtained through lock-in detection are processed employing Chebyshev's polynomial function of the distance between the probe and the sample. The method is first applied to numerically generated near-field evanescent data, with three different decreasing lengths, and then applied to an experimental signal. Therefore the contrast of the signal above nanostructures is discussed to underline the discrepancy between the scanning near-field optical microscopy data and the reconstructions.