Abstract

The spatial resolution of conventional optical measurements is limited by far field diffraction effects. Recently a new optical technique has been demonstrated in which the spatial resolution can be much higher than the diffraction limit. Near-field optical microscopy involves scanning a spot of light, of dimension much smaller than the optical wavelength, in close proximity to the surface of a sample. To form the spot of light, a technique has been developed in which a single mode optical fiber is pulled to an ultrafine tip and coated with aluminum.¹ The tapered fiber tip funnels light through a small aperture (tens of nanometer) whose size determines the near-field spatial resolution. Furthermore, because of the inherently low background signal in these microscopes, emission signals from a single molecule can be detected.²,³

© 1994 Optical Society of America