Nanometer-precise optical length measurement using near-field scanning optical microscopy with sharpened single carbon nanotube probe.

We have developed and characterized a plasmon-excitation scattering-type near-field scanning optical microscope with sharpened single carbon nanotube probe. The developed microscope can optically capture differences in the refractive index of single-nanometer surface structures. Statistical analysis enabled us to estimate the precision of the optical length measurement to 1.8 nm.