Real time suspended particle monitor

• US 6,049,381 A
• Filed: 10/29/1993
• Issued: 04/11/2000
• Est. Priority Date: 10/29/1993
• Status: Expired due to Term

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture, the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Tankersley, Lawrence L., Reintjes, John F., Howard, Paul L., McKenna, Thomas, Mahon, Rita, Duncan, Michael D., Chamberlain, Martin
• Primary Examiner(s): Pham, Hoa Q.
• Application Number:
  US08/143,370
• Time in Patent Office: 2,356 Days
• Field of Search: 356/335-343, 250/574, 250/222.2, 250/39, 250/73
• US Class Current: 356/335
• CPC Class Codes: G01N 15/0227 using imaging; using holography
• CPC Class Codes: G01N 2015/0294 Particle shape
• CPC Class Codes: G01N 2021/177 Detector of the video camera type
• CPC Class Codes: G01P 5/001 Full-field flow measurement, e.g. determining flow velocity and direction in a whole region at the same time, flow visualisation

Abstract

A method and apparatus for real-time monitoring of particulates in a fluid. The fluid is illuminated, and an image formed of the interior of the fluid. The image is then detected, and processed to determine the size, shape, etc. of particulates within the fluid.

Claims

1. An apparatus for the real time monitoring of suspended particulates in a fluid, said apparatus comprising:

a laser light source;

means for collimating an optical beam from said light source;

a fluid chamber for passing a fluid to be examined, said fluid chamber being suitable for illumination by said collimated beam;

means for forming an optical image of the fluid within said fluid chamber; and

means for classifying shapes of particulates in said optical image;

wherein said means for classifying shapes comprises;

a two-dimensional transducer array means for detecting said optical image and

means for comparing, responsive to said means for detecting, shapes of the particulates in the fluid with at least one reference shape.

2. The apparatus of claim 1 wherein:

said light source emits coherent light;

said means for forming an optical image comprises a lens; and

said means for detecting said optical image comprises an array of phototransisters.

3. The apparatus of claim 1 wherein:

said light source emits coherent light; and

said means for detecting said optical image comprises an array of phototransisters.

4. The apparatus of claim 1 wherein:

said light source emits coherent light;

said means for forming an optical image comprises a lens; and

said means for detecting said optical image comprises an array of charge coupled devices.

5. The apparatus of claim 1 further comprising:

a second light source;

a second means for collimating an optical beam from said light source;

a second means for forming an optical image of the fluid within said fluid chamber; and

a second-means for classifying shapes of particulates in said optical image.

6. The apparatus of claim 5 wherein:

said means for classifying shapes of particulates comprises a first means for detecting said optical image and a first means for comparing, responsive to said first means for detecting, shapes of the particulates in the fluid with reference shapes and

said second means for classifying shapes of particulates comprises a second means for detecting said optical image and a second means for comparing, responsive to said second means for detecting, shapes of the particulates in the fluid with reference shapes.

7. The apparatus of claim 6 wherein:

said first means for classifying shapes of particulates comprises a first memory means for storing information relating to reference shapes and a first means for processing said information relating to reference shapes with information from said first means for detecting said optical image to classify the shapes of particulates within said fluid captured in said optical image and

said second means for classifying shapes of particles comprises a second memory means for storing information relating to reference shapes and a second means for processing said information relating to reference shapes with information from said second means for detecting said optical image to classify the shapes of particulates within said fluid captured in said optical image.

8. The apparatus of claim 1, wherein said means for comparing comprises:

means for storing in computer memory a reference shape indicative of a particulate shape having a circular cross-section;

electronic means for comparing said reference shape to said optical image effective to identify particulates whose shape matches said reference shape.

9. The apparatus of claim 1, wherein said apparatus comprises Hough transform means for removing rotational and size dependance of said particulates in said optical image.

10. The apparatus of claim 1, wherein said means for comparing comprises a means for spatially correlating said image and said reference shape.

11. The apparatus of claim 1, wherein said electronic means is a neural net adapted to compare said reference shape to said image.

12. The apparatus of claim 1, wherein said means for comparing comprises:

means for forming a transformed image by performing a spatial Fourier transform on said image;

means for comparing a preselected spatial Fourier spectrum to said transformed image.

13. The apparatus of claim 1, wherein said light source is a pulsed light source.

14. A method for the real time monitoring of suspended particulate matter in a fluid, said method comprising the steps of:

a) illuminating a fluid with a laser beam;

b) forming an optical image of the illuminated fluid;

c) detecting said optical image of the fluid with a two-dimensional transducer array; and

d) analyzing said optical image of the fluid wherein said analyzing comprises;

retrieving from computer memory at least one particulate matter reference shape;

electronically comparing said image to said at least one particulate matter reference shape to match said at least one reference shape to shapes present in said image.

15. The method of claim 14 wherein:

the fluid is illuminated by a, collimated optical beam and the optical image is analyzed by a microprocessor.

16. The method of claim 14 wherein:

the fluid is illuminated by a, collimated optical beam and the optical image is analyzed by an optical correlator.

17. The method of claim 14 wherein:

the fluid is,illuminated by a, collimated optical beam and the optical image is analyzed by a neural network.

18. The method of claim 14, wherein said method comprises applying a Hough transform to said image effective to remove rotational and size dependance of said particulate matter in said image.

19. The method of claim 14, wherein said analyzing comprises spatially correlating said image and said particulate matter reference shape.

20. The method of claim 14 wherein said electronically comparing comprises using a neural net to compare said particulate matter reference shape to said image.

21. The method of claim 14, wherein said electronically comparing comprises spatial correlating said image and said at least one particulate matter reference shape.

22. The method of claim 14, wherein said electronically comparing comprises:

forming a Fourier transform of said image;

comparing a preselected spatial Fourier spectrum to said Fourier transform of said image.

23. The method of claim 14 wherein said illuminating employs pulsed illumination.

24. An apparatus for the real time monitoring of suspended particulates in a fluid, said apparatus comprising:

a laser light source;

means for collimating an optical beam from said light source;

a fluid chamber for passing a fluid to be examined, said fluid chamber being suitable for illumination by said collimated optical beam;

means for optical phase conjugation of said collimated beam on the side of said fluid chamber opposite to that which said light enters said chamber;

a first imaging means, arranged between said fluid chamber and said means for optical phase conjugation for focusing said collimated beam exiting said fluid chamber onto said phase conjugation means;

a second imaging means for forming an optical image of the fluid within said fluid chamber by capturing said collimated beam after said collimated beam has propagated from said optical phase conjugation means through said fluid chamber; and

wherein each of said first and said second imaging means is a two-dimensional opto-electric array; and

wherein said apparatus further comprises means for processing said optical image.

25. The apparatus of claim 24 wherein:

said light source emits coherent light;

said means for forming an optical image comprises a lens; and

said means for detecting said optical image comprises an array of phototransisters.

26. The apparatus of claim 24 wherein:

said light source emits coherent light; and

said means for detecting said optical image comprises an array of phototransisters.

27. The apparatus of claim 24 wherein:

said light source edits coherent light;

said means for forming an optical image comprises a lens; and

said means for detecting said optical image comprises an array of charge coupled devices.

28. The apparatus of claim 24, wherein said means for processing comprises:

electronic means for comparing said reference shape to said optical image effective to identify particulate whose shape matches said reference shape.

29. The apparatus of claim 28 wherein said apparatus comprises Hough transform means for removing rotational and size dependance of said particulate in said optical image.

30. The apparatus of claim 28, wherein said electronic means comprises means for spatially correlating said image and said reference shape.

31. The apparatus of claim 28 wherein said electronic means is a neural net adapted to compare said reference shape to said image.

32. The apparatus of claim 28, wherein said electronic means comprises a spatial correlator for correlating said image and said at least one reference shape.

33. The apparatus of claim 24, wherein said means for processing comprises:

means for forming a transformed image by performing a spatial Fourier transform on said image;

means for comparing a preselected spatial Fourier spectrum to said transformed image.

34. The apparatus of claim 24 wherein said light source is a pulsed light source.