System and method for individual particle sizing using light scattering techniques

Patent metadata

Field	Value
Publication number	US-10634598-B2
Application number	US-201515764833-A
Country	US
Kind code	B2
Filing date	Oct 2, 2015
Priority date	Oct 2, 2015
Publication date	Apr 28, 2020
Grant date	Apr 28, 2020

Abstract

A particle sizing system is provided that includes an optical source generating a light beam for illuminating particles in a monitored volume, a plurality of light deflectors, each positioned to receive and deflect light scattered by the particles, and an image capture device collecting scattered light deflected by each light deflector. The image capture device outputs an image including a plurality of sub-images, each generated from the collected light deflected from a respective one of the light deflectors. Each particle is imaged as a spot in each sub-image, the plurality of spots associated with each particle corresponding to a plurality of scattering angles. The system also includes a processing unit configured to identify the spots associated with the each particle in the sub-images, compute a spot parameter associated with each spot, and determine the size of each particle from its related spot parameters. A particle sizing method is also provided.

First claim

The invention claimed is:

1. A particle sizing system, comprising:
an optical source generating a light beam, the light beam illuminating particles contained in a monitored volume;
a plurality of light deflectors, each light deflector being positioned to receive and deflect light scattered by the illuminated particles;
an image capture device collecting deflected scattered light from each light deflector, the image capture device outputting an image comprising a plurality of sub-images, each sub-image being generated from the collected light deflected from a respective one of the plurality of light deflectors, each illuminated particle being imaged as a spot in each of the plurality of sub-images, the plurality of spots associated with each illuminated particle corresponding to light scattered at a plurality of scattering angles; and
a processing unit receiving the image from the image capture device, the processing unit being configured to, for each illuminated particle, identify the plurality of spots associated with the illuminated particle in the plurality of sub-images, determine a spot parameter associated with each of the plurality of spots, and determine a size of the illuminated particle from the plurality of spot parameters.

2. The particle sizing system according to claim 1 , wherein each light deflector is positioned to deflect a respective forward scattered component of the light scattered by the particles.

3. The particle sizing system according to claim 2 , wherein, for each illuminated particle, each one of the plurality of scattering angles is smaller than 35° with respect to a propagation direction of the light beam.

4. The particle sizing system according to claim 1 , wherein the plurality of light deflectors consists of three light deflectors.

5. The particle sizing system according to claim 1 , wherein the plurality of light deflectors consists of a plurality of light reflectors.

6. The particle sizing system according to claim 5 , wherein the plurality of light reflectors comprises plane mirrors.

7. The particle sizing system according to claim 1 wherein surfaces normals of the plurality of the light deflectors are all parallel to a common plane.

8. The particle sizing system according to claim 1 , wherein each light deflector is positioned such that the scattered light deflected thereby reaches the image capture device without crossing the optical axis of the light beam.

9. The particle sizing system according to claim 1 , wherein the optical source is a laser source or a light-emitting diode source.

10. The particle sizing system according to claim 1 , further comprising a beam conditioning element for converting the light beam into a fan-shaped beam.

11. The particle sizing system according to claim 1 , further comprising a housing enclosing at least the plurality of light deflectors and the image capture device, the housing comprising an optical window for allowing part of the light scattered by the particles to be transmitted inside the housing and reach the plurality of light deflectors.

12. The particle sizing system according to claim 1 , wherein, for each illuminated particle, the processing unit is configured to determine, as the spot parameter, an energy parameter indicative of an amount of optical energy contained in the spot associated with the illuminated particle.

13. The particle sizing system according to claim 1 , wherein the processing unit is configured to determine the size of each illuminated particle from one or more ratios of the spot parameters associated with the illuminated particle.

14. The particle sizing system according to claim 1 , wherein the processing unit is configured to determine the size of each illuminated particle from a comparison of the plurality of spot parameters with reference data.

15. The particle sizing system according to claim 14 , wherein the reference data is obtained from a numerical model based on the Mie scattering theory.

16. An imaging module for use in a particle sizing system, the imaging module comprising:
a plurality of light deflectors, each light deflector being positioned to receive and deflect light scattered by particles contained in a monitored volume and illuminated by a light beam; and
an image capture device collecting deflected scattered light from each light deflector, the image capture device outputting an image including a plurality of sub-images, each sub-image being generated from the collected light deflected from a respective one of the plurality of light deflectors, each illuminated particle being imaged as a spot in each of the plurality of sub-images, the plurality of spots associated with each illuminated particle corresponding to light scattered at a plurality of scattering angles and being characterized by respective spot parameters, a combination of the plurality of spot parameters being indicative of a size of the illuminated particle associated therewith.

17. The imaging module according to claim 16 , further comprising a housing enclosing the plurality of light deflectors and the image capture device, the housing comprising an optical window for allowing part of the light scattered by the particles to be transmitted inside the housing and reach the plurality of light deflectors.

18. The imaging module according to claim 16 , in combination with a non-transitory computer readable memory storing computer executable instructions thereon that when executed by a computer perform the steps of:
receiving the image acquired by the image capture device; and, for each illuminated particle,
identify the plurality of spots associated with the illuminated particle in the plurality of sub-images, determine the spot parameter associated with each of the plurality of spots, and determine the size of the illuminated particle from the plurality of spot parameters.

19. A non-transitory computer readable memory storing computer executable instructions thereon that when executed by a computer perform the steps of:
receiving an image from an imaging module for use in a particle sizing system, the imaging module comprising:
a plurality of light deflectors, each light deflector being positioned to receive and deflect light scattered by particles contained in a monitored volume and illuminated by a light beam; and
an image capture device collecting deflected scattered light from each light deflector, the image capture device outputting an image including a plurality of sub-images, each sub-image being generated from the collected light deflected from a respective one of the plurality of light deflectors, each illuminated particle being imaged as a spot in each of the plurality of sub-images, the plurality of spots associated with each illuminated particle corresponding to light scattered at a plurality of scattering angles and being characterized by respective spot parameters, a combination of the plurality of spot parameters being indicative of a size of the illuminated particle associated therewith; and, for each illuminated particle,

identify the plurality of spots associated with the illuminated particle in the plurality of sub-images, determine the spot parameter associated with each of the plurality of spots, and determine the size of the illuminated particle from the plurality of spot parameters.

20. A particle sizing method comprising the steps of:
illuminating particles contained in a monitored volume;
receiving and deflecting light scattered by the illuminated particles with a plurality of light deflectors;
collecting

Assignees

• Institut Nat Doptique

Inventors

• Cantin Daniel

Classifications

• G01N15/06

  Investigating concentration of particle suspensions (by weighing G01N5/00; investigating sedimentation of particle suspensions G01N15/04; investigating individual particles G01N15/10) · CPC title

• G01N2015/0046

  in gas, e.g. smoke · CPC title

• G01N15/0211 Primary

  Investigating a scatter or diffraction pattern · CPC title

• G01N15/1459

  the analysis being performed on a sample stream · CPC title

• G01N2015/1486

  Counting the particles · CPC title