Focused evanescent field under radially polarized beam illumination

In order to eliminate the focus deformation and at the same time localize the field near the interface, a tightly focused evanescent field combining with a radially polarized illumination, generated by interference method with a single LCD, is proposed in this paper. A scanning near-field optical microscope (SNOM) has been employed to observe the focal spot near the interface by means of directly scanning over the focal field.