US 6,100,976 A · Method and apparatus for fiber optic multiple scattering suppression

Abstract

The instant invention provides a method and apparatus for use in laser induced dynamic light scattering which attenuates the multiple scattering component in favor of the single scattering component. The preferred apparatus utilizes two light detectors that are spatially and/or angularly separated and which simultaneously record the speckle pattern from a single sample. The recorded patterns from the two detectors are then cross correlated in time to produce one point on a composite single/multiple scattering function curve. By collecting and analyzing cross correlation measurements that have been taken at a plurality of different spatial/angular positions, the signal representative of single scattering may be differentiated from the signal representative of multiple scattering, and a near optimum detector separation angle for use in taking future measurements may be determined.

Claims18

Dependent claims

A method of determining a particle size using dynamic light scattering, wherein is provided a sample containing a plurality of particles, comprising the steps of:

(a) directing a laser light beam at the sample, thereby creating a speckle field containing at least a multiply scattered signal and a singly scattered signal;
(b) orienting a first detector so as to detect a predetermined portion of the speckle field;
(c) orienting a second detector so as to detect substantially the same predetermined portion of the speckle field, said second detector being aligned at a predetermined small angle with respect to said first detector;
(d) simultaneously detecting the predetermined portion of the speckle field within said first detector and said second detector, thereby creating a first detector signal and a corresponding second detector signal;
(e) performing steps (b) to (d) at a plurality of different predetermined small angles, thereby producing a plurality of first detector signals and a corresponding plurality of second detector signals;
and,
(f) determining an estimate of the particle size using said plurality of first detector signals and said corresponding plurality of second detector signals.

4 more elements

A method of attenuating multiple scattering in dynamic light scattering measurements, wherein is provided a sample containing particles, comprising the steps of:

(a) directing a laser light beam at the sample, thereby creating a speckle field having a multiple scattering component and a single scattering component;
(b) orienting a first detector to detect a predetermined portion of the speckle field;
(c) orienting a second detector to detect substantially a same predetermined portion of the speckle field, said second detector being aligned at a predetermined small angle with respect to said first detector;
(d) simultaneously detecting the predetermined portion of the speckle field within said first detector and said second detector, thereby creating a first detector signal and a second detector signal;
(e) cross correlating said first detector signal and said second detector signal, thereby producing an intensity cross correlation value;
(f) performing steps (b) to (e) at a plurality of different predetermined small angles, thereby producing a plurality of intensity cross correlation values;
and,
(g) determining from said plurality of intensity cross correlation values an optimizing detector angle between said first detector and said second detector, whereat said multiple scattering component is attenuated and whereat said single scattering component predominates.

5 more elements

Dependencies are inferred from the claim text.

Method and apparatus for fiber optic multiple scattering suppression

Life of this patent

Method and apparatus for fiber optic multiple scattering suppression

Life of this patent

Abstract

Claims18