Non-orthogonal particle detection systems and methods

• US 8,027,035 B2
• Filed: 03/08/2011
• Issued: 09/27/2011
• Est. Priority Date: 12/04/2007
• Status: Active Grant

• Current Assignee: Particle Measuring Systems Incorporated (Spectris PLC)
• Original Assignee: Particle Measuring Systems Incorporated (Spectris PLC)
• Inventors: Sandberg, Legal Representative, Karen R., Sandberg, Jon, Sehler, Dwight A., Mitchell, John
• Primary Examiner(s): Punnoose; Roy M
• Application Number:
  US13/043,305
• Publication Number:
  US 20110155927A1
• Time in Patent Office: 203 Days
• Field of Search: 356335-338, 356/340, 356/342
• US Class Current: 356/336
• CPC Class Codes: G01N 15/1433 using image recognition
• CPC Class Codes: G01N 15/1459 the analysis being performed on a sample stream
• CPC Class Codes: G01N 2015/0038 Investigating nanoparticles
• CPC Class Codes: G01N 2015/025 Methods for single or grouped particles
• CPC Class Codes: G01N 2015/1402 Data analysis by thresholding or gating operations performed on the acquired signals or stored data

Abstract

Described herein is a particle detection system capable of spatially resolving the interaction of particles with a beam of electromagnetic radiation. Using a specific electromagnetic beam cross sectional shape and orientation, the detection sensitivity of a particle detection system can be improved. Also provided are methods for detecting and sizing particles in a manner that has low background signal and allows for spatially resolving the scattering or emission of electromagnetic radiation from particles.

Claims

1. A particle detection system comprising:

a flow cell for containing a fluid flowing through said flow cell in a flow direction;

a source for generating a beam of electromagnetic radiation having a cross sectional profile having a major axis and a minor axis, said source positioned to direct said beam through said flow cell, wherein an angle between said major axis and said flow direction is non-orthogonal, wherein particles contained within said fluid interact with said beam, thereby generating scattered or emitted electromagnetic radiation;

a system of optics for collecting and directing said scattered or emitted electromagnetic radiation onto a two-dimensional detector, wherein said system of optics has an optical axis positioned non-orthogonal to said major axis; and

said two-dimensional detector positioned in optical communication with said flow cell for receiving at least a portion of said scattered or emitted electromagnetic radiation, wherein said two-dimensional detector is positioned non-orthogonal to said optical axis of said system of optics.

2. The particle detection system of claim 1, wherein said two-dimensional detector comprises an array of detector elements positioned such that a plurality of said detector elements receives said scattered or emitted electromagnetic radiation.

3. The particle detection system of claim 1, wherein said angle is selected from the range of 5°

to 85°

.

4. The particle detection system of claim 1 wherein said cross sectional profile has a shape that is elliptical or rectangular.

5. The particle detection system of claim 1, wherein said cross sectional profile has a width along said minor axis selected from between 5 μ

m and 100 μ

m.

6. The particle detection system of claim 1, wherein said cross sectional profile has a width along said major axis selected from between 50 μ

m and 1200 μ

m.

7. The particle detection system of claim 1, wherein said cross sectional profile has a width along said major axis extending to or beyond edges of said flow cell.

8. The particle detection system of claim 1, wherein said flow cell has a cross sectional profile having a first longer side parallel to a propagation axis of said beam and a second shorter side perpendicular to said propagation axis of said beam.

9. The particle detection system of claim 8, wherein said first longer side has a width selected from 0.25 mm to 10 mm.

10. The particle detection system of claim 8, wherein said second shorter side has a width selected from 80 μ

m to 500 μ

m.

11. The particle detection system of claim 8, wherein an aspect ratio of said flow cell is greater than or equal to 20.

12. The particle detection system of claim 1, wherein a propagation axis of said beam is orthogonal to said flow direction.

13. The particle detection system of claim 1, wherein a propagation axis of said beam is non-orthogonal to said flow direction.

14. The particle detection system of claim 1, wherein said system of optics images said scattered or emitted radiation onto said two-dimensional detector.

15. The particle detection system of claim 1, wherein said scattered or emitted electromagnetic radiation is focused by said system of optics to a spot on said two-dimensional detector having a size selected from between 5 μ

m to 80 μ

m.

16. The particle detection system of claim 1, wherein said two-dimensional detector has an orientation positioned to allow for a sharply focused image of said scattered or emitted electromagnetic radiation across an active area of said two-dimensional detector.

17. The particle detection system of claim 1, wherein said two-dimensional detector has an orientation positioned for providing a spatially resolved image of said scattered or emitted electromagnetic radiation, wherein said scattered or emitted electromagnetic radiation is spatially resolved along a first axis parallel to a propagation axis of said beam and a second axis parallel to said major axis of said cross sectional profile of said beam.

18. The particle detection system of claim 1, wherein said two-dimensional detector performs time delay integration.

19. A method of detecting particles, said method comprising the steps of:

providing particles in a fluid having a flow direction;

passing a beam of electromagnetic radiation having a cross sectional profile having a major axis and a minor axis through said fluid, wherein an angle between said major axis and said flow direction is non-orthogonal, and wherein said particles interact with said beam thereby generating scattered or emitted electromagnetic radiation;

collecting and directing said scattered or emitted electromagnetic radiation onto a two-dimensional detector using a system of optics wherein said system of optics has an optical axis positioned non-orthogonal to said major axis; and

detecting at least a portion of said scattered or emitted electromagnetic radiation using said two-dimensional detector, wherein said two-dimensional detector is positioned non-orthogonal to said optical axis of said system of optics, thereby detecting said particles.

20. A method of spatially resolving an interaction of particles with a beam of electromagnetic radiation, said method comprising the steps of:

providing particles suspended within a fluid flowing in a flow direction;

passing a beam of electromagnetic radiation through said fluid, wherein said beam has a cross sectional profile having a major axis and a minor axis and wherein an angle between said major axis and said flow direction is non-orthogonal, and wherein said particles interact with said beam thereby generating scattered or emitted electromagnetic radiation;

collecting and directing said scattered or emitted electromagnetic radiation onto a two-dimensional detector using a system of optics, wherein said system of optics has an optical axis positioned non-orthogonal to said major axis, wherein said two-dimensional detector is positioned non-orthogonal to said optical axis of said system of optics,

detecting at least a portion of said scattered or emitted electromagnetic radiation using said two-dimensional detector, thereby spatially resolving said scattered or emitted electromagnetic radiation in a first direction parallel to a propagation axis of said beam and in a second direction parallel to said major axis of said cross sectional profile of said beam.

21. A method of sizing a particle, the method comprising the steps of:

providing a particle suspended within a fluid flowing in a flow direction through a flow cell;

passing a beam of electromagnetic radiation through said fluid, wherein said beam has a cross sectional profile having a major axis and a minor axis and wherein an angle between said major axis and said flow direction is non-orthogonal, and wherein said particle interacts with said beam thereby generating scattered or emitted electromagnetic radiation;

collecting and directing said scattered or emitted electromagnetic radiation onto a two-dimensional detector using a system of optics, wherein said system of optics has an optical axis positioned non-orthogonal to said major axis, wherein said two-dimensional detector is positioned non-orthogonal to said optical axis of said system of optics,

imaging at least a portion of said scattered or emitted electromagnetic radiation onto the two-dimensional detector;

determining an intensity of said scattered or emitted electromagnetic radiation imaged onto said two-dimensional detector; and

comparing said intensity of said scattered or emitted electromagnetic radiation imaged onto said two-dimensional detector with one or more threshold reference values, thereby determining a size of said particle.