Analysis of the influence of the tip vibration in the formation of images in apertureless scanning near-field optical microscopy
Résumé
The theoretical influence of the vertical vibration of the tip is investigated to calculate the images of a quartz grating in an apertureless scanning near-field optical microscope configuration, a realistic model is used for the simulation of the lock-in detection. It is shown that the output signal issued from the lock-in detection cannot be simply approximated by a mere difference between the intensities of the field between the top and bottom positions of the tip oscillation. Several modes of the lock-in detection, amplitude and phase, X and Y channels, at the fundamental frequency or for the following harmonics, though all leading to images containing high spatial frequencies of the grating, show significant differences that can induce misinterpretations in specific cases.