MODE-SELECTIVE DYNAMIC LIGHT-SCATTERING - THEORY VERSUS EXPERIMENTAL REALIZATION

We present a quantitative experimental comparison of fiber-based, sing le- and few-mode dynamic light scattering with the classical pinhole-d etection optics. The recently presented theory of mode-selective dynam ic light scattering [Appl. Opt. 32, 2860 (1993)] predicts a collection efficiency and a signal-to-baseline ratio superior to that of a class ical pinhole setup. These predictions are confirmed by our experiments . Using single-mode optical fibers with different cutoff wavelengths a nd commercially available mechanical components, we have constructed a mode-selective detection optics in a simple and compact dynamic light -scattering spectrometer that permits an optimal compromise between si gnal intensity and dynamical resolution.