Superresolution In Confocal Imaging

The resolving power of an image-forming instrument is limited by the highest spatial frequency transmitted by the system. In a more traditional definition the resolution limit is determined to the shape of the point-spread function of the instrument. Diffraction does not constitute a fundamental limit to resolution. For example, when the image is built up point by point, the contribution of each image element can be separated from the other in time, so that, in principle, more information can be obtained about the spatial characteristics of a stationary object. This has been demonstrated in near-field optical scanning microscopy, where a tenfold resolution gain has been achieved over the half-wavelength limit'.