Near-Field Microscopy by Elastic Scattering from a Tip

Near-Field Microscopy by Elastic Scattering from a Tip 

We wrote earlier that the use of an aperture for SNOM was essentially precluded because of the extremely low transmission of narrow metalized glass fibers caused by the waveguide cutoff effect. Several workers recognized the potential of achieving better resolution by using a small scatterer instead of a small aperture [12-16] because an illuminated particle can exhibit enhanced optical fields in its neighborhood that is in turn modified by the presence of a sample. As a result of this near-field interaction, scattered light that is measured in the far field contains 

The effect of the material from which the AFM tips were constructed was investigated by Haefliger et al. [26]. They showed that the low refractive index of the thin oxide layer on the surface of Si tips reduced the antenna effect and therefore 

The early results reported by Hillenbrand s group were achieved by illuminating the AFM tip with a continuous-wave laser, which gave good images but limited the spectral range that can be covered to the output wavelengths of the laser. A related limitation is found when pulses of infrared radiation from a femtosecond laser 

This approach was validated by mapping an approximately 1 pm thick p-doped polycrystalline silicon film sandwiched on each side by a 1 pm thick film of silica. 

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