US 9,435,726 B2 · Dynamic and depolarized dynamic light scattering colloid analyzer

Abstract

Apparatus are described for measuring the characteristics of colloidal particles suspended in transparent media by Dynamic Light Scattering (DLS) and Depolarized Dynamic Light Scattering (DDLS) into regions where conventional measurements are difficult or impractical. Matching the diameter of an illuminating beam and an intersecting diameter of a field stop image extends measurements into regions that include concentrated turbid suspensions that frequently appear so visually opaque that multiple scattering typically gives a falsely low estimate of particle size. At the opposite extreme, where insufficient signal is available to determine either or both of the translational and/or rotational relaxation times of the particles, typically where they are too small, too few, or of insufficient refractive index difference from the medium to scatter enough light, measurements can be improved by: a) using a sufficiently large aperture such that many coherence areas fall upon the detector; and b) optical homodyne amplification of the scattered signal.

Claims20

Dependent claims

A system for analyzing a specimen having a suspension of particles by light scattering, the system comprising:

a sample region configured to hold the specimen;
a light source and a focusing lens arranged to illuminate an illumination volume at the sample region, wherein the illumination volume has a first diameter;
a detector and a receiving lens system arranged to receive scattered light from at least a portion of the illumination volume, wherein the receiving lens system comprises at least one lens and an adjustable aperture located adjacent to the at least one lens and wherein setting a diameter of the adjustable aperture determines a range of scattering angles of the scattered light collected by the detector and does not change a size of the illumination volume;
and
a field stop located adjacent to the detector, wherein a conjugate image of the field stop formed by the receiving lens defines a second diameter of a visible volume at the sample region, and wherein the system provides optical signals at the detector that enable characterization of particle properties at a fractional concentration of the particles in the suspension as high as 0.1 for particle sizes greater than 100 nm.

2 more elements

Dependencies are inferred from the claim text.

Dynamic and depolarized dynamic light scattering colloid analyzer

Life of this patent

Dynamic and depolarized dynamic light scattering colloid analyzer

Life of this patent

Abstract

Claims20