Fig. 1. s-SNOM schematic and physical diagram

Fig. 2. Point-dipole model and COMSOL finite element simulation results

Fig. 3. s-SNOM approach curve of 1Ω，2Ω，3Ω

Fig. 4. AFM topography and1Ω，2Ω，and 3Ω near-field optical imaging of gold-silicon grating sample

Fig. 5. The center of the focused spot changes with time

Fig. 6. AFM topography and s-SNOM imaging map of gold nanoparticle samples

Fig. 7. AFM topography and s-SNOM imaging map of h-BN samples