Electrophoretic light scattering with plural reference beams, apparatus and method

DETAILED DESCRIPTION What is claimed is: 1.
A process for the electrophoretic characterization of fluid-dispersed particles by measurement of electrophoretic light scattering from said particles, said process comprising the steps of (a) generating a light pattern, incident on said particles dispersed within an electrophoretic cell, which light pattern is characterized by (1) a relatively strong beam forming a principal source of scattered light and (2) a plurality of local oscillator beams of relatively low intensity compared to said strong beam, each of said relatively-low intensity beams being incident on said particles at angles different from each other and different from said strong beam, (b) directing said beams of relatively low intensity light, at a variety of angles, into a sample cell wherein the particles to be characterized are subjected to an electrophoretic environment, thence directing light from said cell onto detectors mounted at a plurality of angles around said cell; (c) detecting and measuring, in each detector, a light from one of said plurality of local oscillator beams and light scattered from said strong beam by said particles within said cell at a plurality of angles, as said light leaves said cell, and (d) simultaneously evaluating light scattered at each said angle to distinguish electrophoretic characteristics of said dispersed particles from random diffusion characteristics of said particles.
2.
A process as defined in claim 1 wherein said light source is passed through a diffraction grating such that a peripheral second order beams is more intense and thereupon attenuating the strength of all but one beam, said one beam serving as said strong beam.
3.
A process as defined in claim 1 comprising the additional step of varying the frequency of said light entering said cell by passing through a frequency-shift device and evalulating light scattered from a given sample at different frequencies.
4.
A process as defined in claim 2 comprising the additional step of varying the frequency of said light entering said cell by passing through a frequency-shift device and evaluating light scattered from a given sample at different frequencies