Enhanced resolution of reflection-mode near-field scanning optical microscope by detecting 2/sup nd/ harmonic signals

While conventional optical microscopes have a resolution limit set by the diffraction to a size given by about half the wavelength of light, a near-field scanning optical microscope (NSOM) surpasses this resolution limit and achieves sub-wavelength resolution. A NSOM probe allows us to achieve higher resolution out of optical microscopy by squeezing it through an optical fiber tip (or narrow aperture) since the light is confined only to an area in the order of the size of the fiber tip. However, making a fine aperture is not easy work. The use of a reflection-mode NSOM detecting the second harmonic reflection signals was tried to examine the feasibility study of resolution enhancement.