Apertureless near field optical microscopy.

摘要

A near field optical microscopy method and apparatus eliminates the necessity of an aperture for scanning a sample surface (18) and greatly reduces the detected background signal. A small dimension tip (14), on the order of atomic dimension, is disposed in close promity to the sample surface (18). A dither motion is applied to the tip (14) at a first frequency in a direction substantially normal (22) to the plane of the sample surface (18). Dither motion is simultaneously applied to the sample (20) at a second frequency in a direction substantially parallel (24) to the plane of the sample surface (18). The amplitude of the motions are chosen to be comparable to the desired measurement resolution. The end (12) of the tip (14) is illuminated by optical energy. The scattered light from the tip (14) and surface (18) is detected at the difference frequency for imaging the sample surface (18) at sub-wavelength resolution without the use of an aperture. Alternatively, the tip (14) is maintained stationary and the sample (20) undergoes motion in the two directions.