Systems and methods for use in detecting harmful aerosol particles

• US 20060232776A1
• Filed: 02/08/2006
• Published: 10/19/2006
• Est. Priority Date: 02/08/2005
• Status: Active Grant

• Current Assignee: Northrop Grumman Systems Corporation (Northrop Grumman Corporation)
• Original Assignee: Northrop Grumman Corporation
• Inventors: Freidhoff, Carl B., Hairston, Peter P.
• Granted Patent: US 7,554,663 B2
• Time in Patent Office: Days
• US Class Current: 356/388
• CPC Class Codes: G01J 2003/1213 Filters in general, e.g. dichroic, band
• CPC Class Codes: G01J 2003/1217 Indexed discrete filters or choppers
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/10 Arrangements of light sources specially adapted for spectrometry or colorimetry
• CPC Class Codes: G01J 3/32 Investigating bands of a spectrum in sequence by a single detector
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01J 3/427 Dual wavelengths spectrometry
• CPC Class Codes: G01J 3/4406 Fluorescence spectrometry
• 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 2015/019 Biological contaminants; Fouling
• CPC Class Codes: G01N 2015/144 Imaging characterised by its optical setup
• CPC Class Codes: G01N 2021/6417 Spectrofluorimetric devices
• CPC Class Codes: G01N 2021/6419 Excitation at two or more wavelengths
• CPC Class Codes: G01N 2021/6421 Measuring at two or more wavelengths
• CPC Class Codes: G01N 2021/6467 Axial flow and illumination
• CPC Class Codes: G01N 2021/6482 Sample cells, cuvettes
• CPC Class Codes: G01N 2021/6484 Optical fibres
• CPC Class Codes: G01N 2021/8592 Grain or other flowing solid samples
• CPC Class Codes: G01N 21/53 : within a flowing fluid, e.g. smoke
• CPC Class Codes: G01N 21/645 : Specially adapted constructive features of fluorimeters
• CPC Class Codes: G01N 21/6486 : Measuring fluorescence of biological material, e.g. DNA, RNA, cells G01N21/6428 takes precedence
• CPC Class Codes: G01N 21/65 : Raman scattering
• CPC Class Codes: G01N 21/85 : Investigating moving fluids or granular solids

Abstract

The invention provides systems and methods for detecting aerosols. The systems and methods can be used to detect harmful aerosols, such as, bio-aerosols.

Claims

1. A detector system, comprising:

an emitter configured to emit excitation energy into a region of space such that a particle located within said region of space may be exposed to the excitation energy;

a detector having a detector input;

a first filter disposed in front of a first portion of the detector input;

a second filter disposed in front of a second portion of the detector input; and

one or more optical elements being configured such that (a) when a particle is located at a first position within said region and exposed to the excitation energy and produces a first emission, at least a portion of the first emission is directed by the one or more optical elements so that said portion of the first emission passes through the first filter prior to reaching the detector input but substantially no portion of the first emission passes though the second filter, and (b) when the particle is located at a second position within said region and exposed to the excitation energy and produces a second emission, at least a portion of the second emission is directed by the one or more optical elements such that said portion of the second emission passes through the second filter prior to reaching the detector input but not the first filter.

2. The detector system of claim 1, wherein the first emission comprises a first wavelength and a second wavelength and the second emission comprises the first and second wavelengths, wherein the first filter is configured to block the first wavelength so that when the particle is located in the first position the first wavelength does not reach the detector input.

3. The detector system of claim 2, wherein the second filter is configured to block the second wavelength so that when the particle is located in the second position the second wavelength does not reach the detector input.

4. The detector system of claim 3, further comprising a data processor configured to determine the intensity of the first wavelength emission and the intensity of the second wavelength emission based on the timing and/or sequence of outputs signals from the detector.

5. The detector system of claim 1, further comprising a data processor, wherein the data processor is configured to distinguish particles of a given composition type from other particles of other composition types based on comparisons of data generated by the detector to data generated from prior assays of particles of the given composition type.

6. The detector system of claim 5, wherein the data processor is configured to distinguish biological particles from non-biological particles.

7. The detector system of claim 1, wherein the detector system includes only said detector and no other detectors.

8. The detector system of claim 1, wherein said detector is a photomultiplier.

9. The detector system of claim 1, further comprising a second detector that detects when a single particle is within said region of space or about to enter said region of space.

10. The detector system of claim 9, further comprising an emitter controller that is configured to cause the emitter to emit radiation in response to the second detector detecting that a single particle is within said region of space or about to enter said region of space.

11. The detector system of claim 1, wherein the emitter is a laser or light emitting diode.

12. The detector system of claim 1, wherein said emissions from said particle include one or more of elastically scattered light, fluorescence, and Raman emissions.

13. The detector system of claim 1, wherein the wavelength or wavelengths of the excitation energy are between about 250 nanometers and 700 nanometers.

14. A detection method, comprising:

obtaining or making a detector system comprising;

an emitter configured to emit excitation energy into a region of space so that a particle located within said region of space may be exposed to the excitation energy;

an emission detector having a detector input;

a first filter disposed in front of a first portion of the detector input; and

a second filter disposed in front of a second portion of the detector input;

emitting from the emitter excitation energy into the region of space;

receiving a moving particle;

directing the moving particle so that the particle passes though a first position in the region of space and a second position in the region of space;

when the particle is in the first position, directing substantially only to the first filter radiation produced as a result of the particle being exposed to the excitation energy emitted into the region of space; and

when the particle is in the second position, directing substantially only to the second filter radiation produced as a result of the particle being exposed to the excitation energy emitted into the region of space.

15. The detection method of claim 14, wherein the radiation resulting from the particle being exposed to the excitation energy emitted into the region of space comprises fluorescent radiation of a first wavelength and/or fluorescent radiation of a second wavelength, wherein the first filter is configured to block the first wavelength fluorescent radiation so that if the particle produces first wavelength fluorescent radiation when the particle is located in the first position, none of said produced first wavelength fluorescent radiation reaches the detector input.

16. The detection method of claim 15, wherein the second filter is configured to block the second wavelength so that if the particle produces second wavelength fluorescent radiation when the particle is located in the second position, none of said produced second wavelength fluorescent radiation reaches the detector input.

17. The detection method of claim 16, further comprising determining the intensity of the first wavelength fluorescent radiation and the intensity of the second wavelength fluorescent radiation emission based on the timing and/or sequence of outputs signals from the detector.

18. The detection method of claim 14, further comprising distinguishing particles of a given composition type from other particles of other composition types based on comparisons of data generated by the detector to data generated from prior assays of particles of the given composition type.

19. The detection method of claim 14, further comprising distinguishing biological particles from non-biological particles based, at least in part on, data generated by the detector.

20. The detection method of claim 14, wherein the detection system includes only said detector and no other detectors.

21. The detection method of claim 14, wherein said detector is a photomultiplier.

22. The detection method of claim 14, further comprising detecting that a single particle is within said region of space or about to enter said region of space.

23. The detection method of claim 22, further comprising causing the emitter to emit radiation in response detecting that a single particle is within said region of space or about to enter said region of space.

24. The detection method of claim 14, wherein the emitter is a laser or light emitting diode.

25. The detection method of claim 14, wherein said radiation produced as a result of the particle being exposed to the excitation energy emitted into the region of space includes one or more of elastically scattered light, fluorescence, and Raman emissions.

26. The method of claim 14, wherein the wavelength or wavelengths of the excitation energy are between about 250 nanometers and 700 nanometers.

27. In a system wherein a fluid contains a first particle and a second particle, a detection method, comprising:

emitting excitation energy into a region of space such that a particle located within said region of space may be exposed to the excitation energy;

directing the fluid containing the first and second particles through the region of space, wherein, when the first particle transits through the region of space, the first particle produces a first emission and, when the second particle transits through the region of space, the second particle produces a second emission, wherein the first particle transits through the region of space before the second particle enters the region of space;

directing the first emission to an emission detector;

directing the second emission to the emission detector;

placing a filter apparatus in front of the emission detector, wherein the first emission passes through the filter apparatus before reaching the emission detector; and

after the first particle has entered the region and before the second particle enters the region, changing a characteristic of the filter apparatus or replacing the filter apparatus with a second filter apparatus so that the second emission passes through the changed filter apparatus or the second filter apparatus before reaching the emission detector.

28. The method of claim 27, further comprising the step of replacing the first filter apparatus with the second filter apparatus at a point in time that is between the time when the first particle exits the region and the time when the second particle enters the region, so that the second emission passes through the second filter apparatus before reaching the emission detector.

29. The method of claim 27, wherein the first filter apparatus comprises a first bandpass filter and the second filter apparatus comprises a second bandpass filter.

30. The method of claim 27, wherein the first filter apparatus comprises a tunable grating, etalon or prism.

31. The method of claim 30, further comprising the step of changing a characteristic of the filter apparatus.

32. The method of claim 30, wherein the first filter apparatus comprises an adjustable dispersion prism or a wavelength tunable etalon.

33. The method of claim 32, wherein the step of changing a characteristic of the filter apparatus comprises adjusting the tunable grating or filter.

34. The method of claim 27, further comprising counting the number of particles that enter the region and performing the step of changing the characteristic of the filter apparatus or replacing the filter apparatus with the second filter apparatus in response to determining that a predetermined number of particles have entered the region.

35. The method of claim 27, further comprising:

for a predetermined amount of time, measuring emissions from particle that enter said region; and

determining whether the predetermined amount of time has elapsed; and

performing said step of changing the characteristic of the filter apparatus or replacing the filter apparatus with the second filter apparatus in response to determining that the predetermined amount of time has elapsed.

36. The method of claim 27, wherein the step of changing the characteristic of the filter apparatus or replacing the filter apparatus with a second filter apparatus occurs after the first particle has passed through the region and before the second particle enters the region.

37. The method of claim 27, wherein the first filter apparatus consists of a first filter and the second filter apparatus consists of a second filter.