Method, apparatus and system for rapid and sensitive standoff detection of surface contaminants

• US 7,796,251 B2
• Filed: 03/20/2007
• Issued: 09/14/2010
• Est. Priority Date: 03/22/2006
• Status: Active Grant

• Current Assignee: Peraton, Inc.
• Original Assignee: ITT Manufacturing Enterprises, Inc. (ITT, Inc.)
• Inventors: Rezac, Jeromy Paul, Kletecka, Christopher Scott, Ponsardin, Patrick Louis
• Primary Examiner(s): Chowdhury; Tarifur
• Assistant Examiner(s): Nur; Abdullahi
• Application Number:
  US11/688,434
• Publication Number:
  US 20070222981A1
• Time in Patent Office: 1,274 Days
• Field of Search: 356/300, 356/301
• US Class Current: 356/301
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0218 using optical fibers
• CPC Class Codes: G01J 3/0272 Handheld
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/44 Raman spectrometry; Scattering spectrometry ; Fluorescence spectrometry
• CPC Class Codes: G01N 21/65 Raman scattering
• CPC Class Codes: G01N 2201/0221 Portable; cableless; compact; hand-held

Abstract

Systems and methods for fast and sensitive standoff surface-hazard detection with high data throughput, high spatial resolution and high degree of pointing flexibility. The system comprises a first hand-held unit that directs an excitation beam onto a surface that is located a distance away from the first unit and an optical subsystem that captures scattered radiation from the surface as a result of the beam of light. The first unit is connected via a link that includes a bundle of optical fibers, to a second unit, called the processing unit. The processing unit comprises a fiber-coupled spectrograph to convert scattered radiation to spectral data, and a processor that analyzes the collected spectral data to detect and/or identify a hazardous substance. The second unit may be contained within a body-wearable housing or apparatus so that the first unit and second unit together form a man-portable detection assembly. In one embodiment, the system can continuously and without interruptions scan a surface from a 1-meter standoff while generating Raman spectral-frames at rates of 25 Hz.

Claims

1. A standoff hazard detection and identification system capable of detecting and identifying contaminants on a surface, comprising:

a first unit that emits a beam of light onto a surface that is located a distance away from the first unit and captures scattered radiation from said surface as a result of said beam of light;

a second unit comprising a spectrograph that converts said scattered radiation to spectral data, wherein the second unit comprises a processor configured to control said second unit to operate in one of first and second modes of operation, where in the first mode, the spectrograph accumulates a relatively small number of returns of scattered radiation for a measurement frame to provide a relatively higher rate for faster scanning on said surface and relatively lower fidelity analysis, and in the second mode, the spectrograph accumulates a relatively high number of returns of scattered radiation for a measurement frame to provide a relatively slower rate for slower scanning on said surface and relatively higher fidelity analysis; and

a link between said first unit and said second unit to couple said scattered radiation from said first unit to said second unit.

2. The system of claim 1, wherein said first unit is a portable hand-held device and comprises a light source that produces the beam of light.

3. The system of claim 1, wherein said light source is an ultraviolet (UV) laser.

4. The system of claim 3, wherein said second unit comprises the UV laser and the first unit comprises a final UV-conversion stage that is pumped by the UV laser in the second unit and coupled to the UV laser via an optical fiber that extends along said link from the second unit to the first unit.

5. The system of claim 1, wherein said first unit comprises a collection optics subsystem that collects said scattered radiation from said surface for coupling via said link to said second unit.

6. The system of claim 5, wherein the first unit comprises a housing having a front window sized to support optical elements associated with a laser light source and the collection optics subsystem, the collection optics subsystem comprising a primary mirror and a secondary mirror, wherein the primary minor is fixed and the secondary mirror is movable along an optical axis and wherein the secondary minor is configured to tip and tilt in order to adjust an optical path for the returned optical energy through the collection optics subsystem.

7. The system of claim 6, wherein the second unit comprises a light source that generates the beam of light and an optical fiber coupled between the light source of the second unit and the first unit, and further comprising an articulated arm connected to a base of the housing of the first unit, wherein the articulated arm is configured to tip and tilt the optical axis of the beam of light.

8. The system of claim 5, wherein the second unit comprises a light source that generates the beam of light and an optical fiber coupled between the light source of the second unit and the first unit, wherein the collection optics subsystem comprises a primary minor, a secondary mirror, and a Raman filter that is configured to separate excitation light that is transmitted through the collection optics subsystem from received scattered radiation that in the same optical path as the excitation light, wherein the primary mirror is movable and the secondary mirror is fixed.

9. The system of claim 5, wherein said first unit comprises a visible target indicator that emits a plurality of beams of visible light through said collection optics subsystem so that the plurality of beams intersect each other on said surface at a focal point of said collection optics subsystem.

10. The system of claim 9, wherein said visible target indicator comprises at least two laser diodes mounted on a housing of said first unit, and a dichroic mirror, wherein the laser diodes are pointed inward into the housing to direct their beams to the dichroic minor which is positioned to reflect beams from the diodes into a bore sight of the first unit through which the light beam is to be directed so that the beams from the diodes intersect each other on said surface at a focal point of said collection optics subsystem.

11. The system of claim 1, wherein said light source generates said beam of light in the ultraviolet (UV) spectrum to induce substances on said surface to emit Raman scattered radiation from said surface.

12. The system of claim 11, wherein said processor compares said spectral data to a plurality of spectral data of known substances, and determines whether said substance is a known or foreign substance.

13. The system of claim 11, wherein said first unit is moved across the surface in order to scan the surface at a scanning rate up to tens of centimeters per second.

14. The system of claim 1, wherein said light source generates said beam of light so as to illuminate a spot that is less than one millimeter in diameter.

15. The system of claim 1, wherein said second unit generates data at a rate of more than 10 measurement frames per second.

16. The system of claim 1, wherein said first unit comprises a collection optics subsystem that collects said scattered radiation from said surface for coupling via said link to said second unit, wherein said collection optics subsystem comprises one or more optical elements that are movable to adjust a focal point of said collection optics subsystem.

17. A standoff hazard detection and identification system capable of detecting and identifying contaminants on a surface from a distance, comprising:

a first unit comprising a light source that emits a beam of light onto a surface that is located a distance away from the first unit and an optical subsystem that captures scattered radiation from said surface as a result of said beam of monochromatic light;

a second unit coupled to said first unit comprising a spectrograph that converts said scattered radiation to spectral data and a processor that analyzes said spectral data in order to detect a contaminant on said surface, said second unit comprising a wireless transceiver configured to wirelessly transmit over the air said spectral data to another device for processing; and

a third unit physically separate from the first unit and second unit and comprising a wireless transceiver that is configured to receive said spectral data from said second unit and a processor that is configured to analyze said spectral data with one or more algorithms that are more computationally intensive than algorithms used by the processor in said second unit;

wherein said processor in said second unit is configured to control said second unit to operate in one of first and second modes of operation, where in the first mode, the spectrograph accumulates a relatively small number of returns of scattered radiation for a measurement frame to provide a relatively higher rate for faster scanning on said surface and relatively lower fidelity analysis, and in the second mode, the spectrograph accumulates a relatively high number of returns of scattered radiation for a measurement frame to provide a relatively slower rate for slower scanning on said surface and relatively higher fidelity analysis.

18. The system of claim 17, wherein said wireless transceiver in the third unit transmits to said second unit results of analysis performed by the processor in said third unit.

19. The system of claim 18, wherein said second unit comprises a user interface and display to display said results.

20. The system of claim 17, wherein second unit comprises a rechargeable power supply, and said third unit comprises a docking port to connect to said second unit in order to exchange information with said second unit, and for supplying electrical energy to charge said rechargeable power supply chargeable batteries of said second unit.

21. A standoff hazard detection system, comprising:

a light source that emits a beam of light onto a surface to excite Raman scattered radiation from said surface;

an optical subsystem that collects the Raman scattered radiation;

a spectrograph that receives the Raman scattered radiation collected by said optical subsystem and generates a measurement frame of Raman spectral data based on an accumulation of a plurality of returns of Raman scattered radiation from said surface; and

a processor that analyzes the Raman spectral data using Raman spectroscopy techniques to discriminate substances on said surface, wherein the processor is configured to control the spectrograph in one of first and second modes, wherein in the first mode, the processor controls the spectrograph to accumulate a relatively small number of returns of scattered radiation for a measurement frame to provide a relatively higher rate for faster scanning on the surface and lower fidelity analysis, and in the second mode, the processor controls the spectrograph to accumulate a relatively high number of returns of scattered radiation for a measurement frame to provide a relatively slower rate for slower scanning of the surface and higher fidelity analysis.

22. A method for standoff detection of a hazardous substance, comprising:

in a first hand-held unit, directing a light beam to a surface located a distance away from the first unit;

in said first unit, capturing returned scattered radiation from said surface as a result of interaction of the light beam with a substance on said surface;

coupling said returned scattered radiation to a second unit separate from said first unit;

generating spectral data from said returned scattered radiation in said second unit in one of first and second modes, wherein in the first mode, generating comprises generating said spectral data from accumulation of a relatively small number of returns of scattered radiation for a measurement frame to provide a relatively higher rate for faster scanning on the surface and lower fidelity analysis, and in the second mode, generating comprises generating said spectral data from accumulation of a relatively high number of returns of scattered radiation for a measurement frame to provide a relatively slower rate for slower scanning of the surface and higher fidelity analysis; and

analyzing said spectral data to detect a contaminant on said surface.

23. The method of claim 22, wherein said analyzing is performed in said second unit.

24. The method of claim 22, and further comprising wirelessly transmitting said spectral data from said second unit to a third unit positioned remotely from said second unit, and wherein said analyzing is performed in said third unit.

25. A man-portable standoff hazard detection apparatus, comprising:

a hand-held unit that directs a light beam onto a surface located a distance away from the hand-held unit and an optical subsystem that captures returned scattered radiation from said surface as a result of said light beam;

a body wearable unit comprising a spectrograph that generates spectral data from the returned scattered radiation, wherein said spectrograph comprises a processor configured to control said second unit to operate in one of first and second modes of operation, where in the first mode, the spectrograph accumulates a relatively small number of returns of scattered radiation for a measurement frame to provide a relatively higher rate for faster scanning on said surface and lower fidelity analysis, and in the second mode, the spectrograph accumulates a relatively high number of returns of scattered radiation for a measurement frame to provide a relatively slower rate for slower scanning on said surface and higher fidelity analysis; and

a cable that connects said hand-held unit to said wearable unit, wherein said cable comprises one or more optical fibers that transports said returned scattered radiation collected by said optical subsystem in said hand-held unit to said spectrograph in said wearable unit.

26. The apparatus of claim 25, wherein said processor of the body wearable unit analyzes said spectral data using spectroscopy techniques to identify a substance on said surface.

27. The apparatus of claim 26, and further comprising a display device in said body wearable unit that is connected to said processor to display information for a substance determined to be present on said surface.

28. The system of claim 25, and further comprising a plurality of hazard detectors each comprising a hand-held unit and an associated body wearable unit, and a central control station wirelessly linked to the plurality of hazard detectors, wherein the central control station is configured to receive detection and identification data from said plurality of hazard detectors and to transmit control signals to the plurality of hazard detectors in order to coordinate a detection sweep of surfaces in a region of interest by the plurality of hazard detectors.

29. The system of claim 28, and further comprising a plurality of base stations connected by a wired network to the central control station, and wherein each base station comprises a radio frequency (RF) transceiver configured to send RF signals to a hazard detector and to receive RF signals from a hazard detector, and wherein the central control station sends the control signals to one or more base stations which in turn wirelessly transmit the control signals as RF signals to one or more hazard detectors.

30. The system of claim 29, wherein each base station further comprises a processor that is configured to analyze spectral data sent via RF signals to the base station from a hazard detector, and wherein the processor in each base station is configured to analyze the spectral data with one or more algorithms that are more computationally intensive than algorithms used by the processor in the body wearable unit of a hazard detector.