Near-Field Optics for Exceeding Diffraction Limits in Spectroscopy and Microscopy.

Abstract

The success of single molecule detection schemes using sheath flow cuvettes as sample cells illustrates the advantage of restricted illumination and probe volume for maximizing detectability or spectroscopy of small objects. The limit to this strategy with conventional optics is diffraction, minimum dimensions of λ/2. The practical limits imposed by physical congestion of optical components may prevent realization of even this limit. The need for optical and spectroscopic characterization of a variety of objects, technological, biological, and chemical, much smaller than λ/2, has driven research toward strategies of optical microscopy with higher resolution.