SYSTEM AND METHOD FOR DETECTING EXPLOSIVES USING SWIR AND MWIR HYPERSPECTRAL IMAGING

Abstract

A system and method for detection of explosive agents using hyperspectral imaging. A system comprising an illumination source, a spectral encoding device, and at least one imaging detector configured for at least one of SWIR and MWIR hyperspectral imaging of a target comprising an unknown material. A method comprising illuminating a target comprising an unknown material, assessing interacted photons using a spectral encoding device, and detecting interacted photons using at least one of SWIR hyperspectral imaging and MWIR hyperspectral imaging. Algorithms and chemometric techniques may be applied to assess the MWIR hyperspectral image to identify the unknown material as comprising an explosive agent or a non-explosive agent. A video imaging device may also be configured to provide a video image of an area of interest, which may be assessed to identify a target for interrogation using SWIR and MWIR hyperspectral imaging.

Description

BACKGROUND

Spectroscopic imaging combines digital imaging and molecular spectroscopy techniques, which can include Raman scattering, fluorescence, photoluminescence, ultraviolet, visible and infrared absorption spectroscopies. When applied to the chemical analysis of materials, spectroscopic imaging is commonly referred to as chemical imaging. Instruments for performing spectroscopic (i.e. chemical) imaging typically comprise an illumination source, image gathering optics, focal plane array imaging detectors and imaging spectrometers.

In general, the sample size determines the choice of image gathering optic. For example, a microscope is typically employed for the analysis of sub micron to millimeter spatial dimension samples. For larger objects, in the range of millimeter to meter dimensions, macro lens optics are appropriate. For samples located within relatively inaccessible environments, flexible fiberscope or rigid borescopes can be employed. For very large scale objects, such as planetary objects, telescopes are appropriate image gathering optics.

For detection of images formed by the various optical systems, two-dimensional, imaging focal plane array (FPA) detectors are typically employed. The choice of FPA detector is governed by the spectroscopic technique employed to characterize the sample of interest. For example, silicon (Si) charge-coupled device (CCD) detectors or CMOS detectors are typically employed with visible wavelength fluorescence and Raman spectroscopic imaging systems, while indium gallium arsenide (InGaAs) FPA detectors are typically employed with near-infrared spectroscopic imaging systems.

Spectroscopic imaging of a sample can be implemented by one of two methods. First, a point-source illumination can be provided on the sample to measure the spectra at each point of the illuminated area. Second, wide-field spectroscopic imaging of a sample can be implemented by collecting spectra over the entire area encompassing the sample simultaneously using an electronically tunable optical imaging filter such as an acousto-optic tunable filter (AOTF) or a liquid crystal tunable filter (“LCTF”). Here, the organic material in such optical filters are actively aligned by applied voltages to produce the desired bandpass and transmission function. The spectra obtained for each pixel of such an image thereby forms a complex data set referred to as a hyperspectral image which contains the intensity values at numerous wavelengths or the wavelength dependence of each pixel element in this image.

Spectroscopic devices operate over a range of wavelengths due to the operation ranges of the detectors or tunable filters possible. This enables analysis in the Ultraviolet (UV), visible (VIS), near infrared (NIR), short-wave infrared (SWIR), mid infrared (MIR) wavelengths, long wave infrared wavelengths (LWIR), and to some overlapping ranges. These correspond to wavelengths of approximately 180-380 nm (UV), 380-700 nm (VIS). 700-2500 nm (NIR), 850-1800 nm (SWIR), 650-1100 nm (MWIR), 400-1100 (VIS-NIR) and 1200-2450 (LWIR).

There currently exists a need for accurate detection of explosive agents. In particular, there exists a need for accurate and reliable detection of explosive agents in standoff and on-the-move (OTM) configurations for both daytime and nighttime operations.

SUMMARY OF THE INVENTION

The present disclosure relates to systems and methods for detecting explosive agents using spectroscopic methods, including imaging. More specifically, the present disclosure provides for systems and methods for explosive detection using short wave infrared (“SWIR”) and mid wave infrared (“MWIR”) hyperspectral imaging. The present disclosure provides for systems and methods that utilize spectral encoding devices and may operate using both passive and active illumination modalities. Therefore, the systems and methods disclosed herein hold potential or daytime and nighttime configurations.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

In the drawings:

FIG. 1 is illustrative of a system of the present disclosure.

FIG. 2 is illustrative of a system of the present disclosure.

FIG. 3 is representative of an algorithm of the present disclosure.

FIG. 4 is representative of a method of the present disclosure.

DETAILED DESCRIPTION

Reference will now be made in detail to the preferred embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

The present disclosure provides for a system and method for detecting hazardous agents, including explosive agents. These explosive materials may be present on or in a target. The target may include, but is not limited to: a location on a vehicle, a vehicle as a whole, a package, a human hand, a passport, a credit card, a driver's license, a boarding pass, a human body part, a piece of human clothing, a human-wearable item, shoes, an airline ticket, baggage, and other items that may have come in contact with a human being. The present disclosure contemplates the target may comprise any item that may need to be scanned for explosive agents to ensure the safety of an area. Additionally, the target may be present in a region of interest of either an indoor or outdoor scene. The technology described herein may be used to detect Improvised Explosive Devices (LEDs), emplacements (such as DE and aged concrete), command wires, EFP wires, disturbed earth, EFP camouflage, and explosive residue, among other materials including but not limited to those associated with explosive compounds and concealments.

Explosive agents, as referred to herein, may include explosive compounds, a residue of an explosive compound, a formulation additive of explosive material, and/or a binder of explosive material. Representative explosive compounds may include but are not limited to: nitrocellulose, Ammonium nitrate (“AN”), nitroglycerin, 1,3,5-trinitroperhydro-1,3,5-triazine (“RDX”), 1,3,5,7-tetranitroperhydro-2,3,5,7-tetrazocine (“HMX”) and 1,3,-Dinitrato-2,2-bis (nitratomethyl) propane (“PETN”). The system and method herein may be used for anomaly detection, countermine research and camouflage concealment and detection through measurements taken from a ground vehicle or aerial vehicle. The invention may be deployed either on a user's vehicle, an unmanned ground vehicle (“UGV”) traveling ahead of them, or an aerial vehicle performing a wide range of surveillance tasks. The present disclosure contemplates that they system and method herein may be applied to other detection scenarios including chemical, biological, a biohazard or an illegal drug.

In one embodiment, the system and method of the present disclosure may operate in a scanning mode, scanning an area of interest to identify a target for interrogation. In another embodiment, the system and method of the present disclosure may operate in a detection mode, interrogating a target comprising an unknown material to identify whether or not an explosive or other hazardous agent is present. The present disclosure also contemplates that the system and method may be configured to operate in a combination scanning/detection configuration. These scanning and detection modes may be operated either sequentially or simultaneously. Simultaneous acquisition of multiple types of data may be accomplished using structured illumination or different light sources.

FIG. 1 is illustrative of a system of the present disclosure. The system may be configured for standoff detection of hazardous agents. In such a configuration, the system may operate in a stationary or on-the-move modality. The system may be mounted on a movable vehicle including but not limited to a car, truck, tank, boat, plane, or other means of transportation.

In one embodiment, the system 100 may comprise a first illumination source 110, configured to illuminate a target comprising an unknown material 120 to thereby generate a plurality of interacted photons. The unknown material may be an explosive agent such as an explosive compound, an explosive residue, or a substance otherwise associated with the use or manufacture of explosives. The unknown material may also comprise a non-explosive agent.

In one embodiment, the illumination source 110 may comprise an active illumination source. This active illumination source may be a broadband light source. The use of an active illumination source holds potential for increasing detection capabilities of a system under low light conditions, such as at night. In another embodiment, the illumination source 110 may comprise a passive illumination source. The passive illumination source may be solar radiation (the sun) or ambient light. In another embodiment, both active and passive illumination may be used.

This illumination may generate a plurality of interacted photons. These interacted photons may comprise photons selected from the group consisting of: photons scattered by the sample, photons absorbed by the sample, photons reflected by the sample, photons transmitted by the sample, photons luminance by the sample, and combinations thereof.

These interacted photons may be collected by one or more collection optics 130. This collection optics 130 may comprise at least one telescope optic, zoom optic, fixed optic, macro/micro combination optic (also referred to herein as a “combination optic”), and combinations thereof. The system of the present disclosure contemplates that it one embodiment, two or more collection optics may be configured so as to collect interacted photons for assessment in two or more different modalities.

These interacted photons may then be assessed using a spectral encoding device 140. In one embodiment, this spectral encoding device 140 may comprise at least one of: a fixed filter, a multivariate optical element, a Fabry-Perot filter, and combinations thereof.

Other embodiments of the present disclosure may utilize a device selected from the group consisting of: an acusto-optical tunable filter (“AOTF”), Evans Split-Element liquid crystal tunable filter, Solc liquid crystal tunable filter, Ferroelectric liquid crystal tunable filter, Fabry Perot liquid crystal tunable filter, a Fabry-Perot etalon, an interferometer, a filter wheel, a fixed filter, a multivariate optical element (“MOE”), a linear variable filter, a pushbroom spectrometer, a fiber array spectral translator (“FAST”) spectrometer, a computed tomography imaging spectrometer, a hybrid filter, and combinations thereof.

Additionally, fixed bandpass and bandreject filters comprised of dielectric, rugate, holographic, color absorption, acousto-optic or polarization types may also be used, either alone or in combination with one of the above LC spectrometers.

An imaging detector 150 may be configured to detect these interacted photons and generate data representative of the target. This data may comprise at least one of: a SWIR spectra, a SWIR image, a MWIR spectra, a MWIR image, and combinations thereof. In another embodiment, this data may comprise at least one of a SWIR hyperspectral image, a MWIR hyperspectral image, and combinations thereof. In one embodiment, an imaging detector may comprise at least one of: an InGaAs detector, an extended range InGaAs detector, an InSb detector, a PtSi detector, and combinations thereof.

In another embodiment, the system 100 may further comprise one or more additional imaging devices to enable the system to operate in multiple modes. In one embodiment, the system 100 may further comprise a video imaging device, which may be a RGB video imaging device, configured so as to output a video image representative of an area of interest comprising the target. This video image may be a dynamic video image, configured for real-time operation in various modes including standoff, stationary, and on-the-move. This video imaging device may also enable the system of the present disclosure to operate in a scanning mode, scanning an area of interest to identify a target for further SWIR and/or MWIR interrogation. In such an embodiment, a user may monitor the video image and identify a target based on at least one of: size, shape, and color of the target. A means for assessing the video image may comprise morphological analysis by a user which may be accomplished by at least one of: visual inspection by user, applying an algorithm, and applying a chemometric technique. Once the target is identified, it may be assessed using SWIR and/or MWIR hyperspectral imaging to determine whether or not it is a hazardous agent.

Other detectors that may be incorporated into the system of the present disclosure to enable additional functional modalities may include: an ICCD detector, a CCD/CMOS detector, a MCT detector, an intervac-intensified detector, a microbolometer, and combinations thereof.

The system 100 may further comprise a means for assessing the hyperspectral image obtained. In one embodiment, processing technology 160 may be configured to assess the hyperspectral image. In one embodiment, the processing technology 160 may comprise a processor such as a single board PC. Other embodiments may contemplate the use of other processing technology including HyperX and PhysX. To assess the MWIR hyperspectral image, the processing technology 160 may be configured so as to apply one or more algorithms 170 including but not limited to: object imaging and tracking, image weighted Bayesian fusion (“IMBF”), simultaneous location and mapping (“SLAM”), scale-invariant feature transform (“SIFT”), hybrid false color, and combinations thereof.

The system 100 may also be configured so as to utilize one or more targeting or sensor positioning systems 180. This may include the use of one or more of a pan tilt unit and a global positioning system (“GPS”). Other targeting or sensor positioning systems contemplated by the present disclosure may include, but are not limited to: a laser range finger, light detection and ranging (“LIDAR”), stereovision, and thermal imaging.

FIG. 2 is illustrative of another embodiment of a system of the present disclosure. In FIG. 2, the system 200, comprises an illumination source 210 configured to illuminate a target comprising an unknown material 220, to thereby generate a plurality of interacted photons. These interacted photons may be collected using at least one collection optics 230. A spectral encoding device 240 may be used to assess these interacted photons. One or more imaging detectors may be configured to detect these interacted photons and generate hyperspectral data representative of the target. In FIG. 2, it is contemplated that two detectors, SWIR detector 250a and MWIR detector 250b, may be configured to generate both SWIR and MWIR data representative of the target. The detectors may be housed in a sensor unit 260.

Processing technology 270 may be configured to apply one or more algorithms 280 and/or chemometric techniques to the hyperspectral images generated to thereby determine whether or not unknown material is an explosive agent.

The system 200 may also be configured so as to utilize one or more targeting or sensor positioning systems 270. This may include the use of one or more of a pan tilt unit and a global positioning system (“GPS”). Other targeting or sensor positioning systems contemplated by the present disclosure may include, but are not limited to: a laser range finger, light detection and ranging (“LIDAR”), stereovision, and thermal imaging.

FIG. 3 is representative of an object imaging and tracking methodology which is contemplated by the present disclosure. In FIG. 3, object A is present in a slightly translated position in every frame, with each frame collected at a different wavelength. The tracking of object A across all n frames allows the spectrum to be generated for every pixel in the object. The same process may be followed for objects B and C. The same process may be followed for n number of objects in a scene. A continual stream of objects may be imaged with defined wavelengths at defined time intervals. Such a methodology may provide the benefit of signal averaging.

One embodiment may comprise the use of hyperspectral addition imaging, more fully described in U.S. patent application Ser. No. 12/799,779, filed on Apr. 30, 2010, entitled “System and Method for Component Discrimination Enhancement Based on Multispectral Addition Imaging,” which is hereby incorporated by reference in its entirety. The present disclosure also contemplates the use of one or more chemometric techniques for assessing MWIR hyperspectral images. These techniques may be applied to compare test data generated by interrogating a target to reference data corresponding to known samples. This reference data may be stored in a reference data base. In one embodiment, a processing technology 160 and/or 270 may be configured to execute a machine readable program code to search a reference database.

Chemometric techniques may include, but are not limited to: principal component analysis (“PCA”), multivariate curve resolution (“MCR”), partial least squares discriminant analysis (“PLSDA”), k means clustering, band t. entropy method, adaptive subspace detector, cosine correlation analysis (“CCA”), Euclidian distance analysis (“EDA”), partial least squares regression (“PLSR”), spectral mixture resolution (“SMR”), a spectral angle mapper metric, a spectral information divergence metric, a Mahalanobis distance metric, a spectral unmixing algorithm, and combinations thereof. A spectral unmixing metric is disclosed in U.S. Pat. No. 7,072,770 entitled “Method for Identifying Components of a Mixture via Spectral Analysis,” which is hereby incorporated by reference in its entirety.

The present disclosure also provides for a method for detecting explosive agents using hyperspectral imaging. One embodiment of such a method is illustrated in FIG. 4. In FIG. 4, the method 400, may comprise illuminating a target comprising an unknown material in step 410 to thereby generate a plurality of interacted photons. These photons may be assessed in step 420 using a spectral encoding device. In step 430, these interacted photons may be detected using at least one imaging detector to thereby generate hyperspectral data representative of the target.

In one embodiment, this data may comprise SWIR data, MWIR data, and combinations thereof. The SWIR data may comprise at least one of a SWIR spectra, a SWIR image, and combinations thereof. In one embodiment, the SWIR data may comprise a SWIR hyperspectral image representative of the target. In one embodiment, the imaging detector may comprise at least one of: an InGaAs detector, an extended range InGaAs detector, and combinations thereof. The MWIR data may comprise at least one of a MWIR spectra, MWIR image, and combinations thereof. In one embodiment, the MWIR data may comprise a MWIR hyperspectral image representative of the target. In one embodiment, the imaging detector may comprise at least one of: an InSb detector, a PtSi detector, and combinations thereof.

In step 440 the hyperspectral image or images are assessed to thereby identify the unknown material as either an explosive agent or a non-explosive agent. This assessment 440 may be achieved by applying one or more algorithms including: object imaging and tracking, image weighted Bayesian fusion, simultaneous location and mapping, scale-invariant feature transform, hybrid false color, and combinations thereof. This assessment, 440 may also be achieved by applying one or more chemometric techniques.

The system and method of the present disclosure also contemplate the use of sensor fusion which may hold potential for increasing the accuracy and reliability of explosive detection. In such an embodiment, processing technology may be configured so as to fuse data from two or more detectors. In one embodiment, sensor fusion may comprise Forensic Integrated Search Technology (“FIST”) available from ChemImage Corporation, Pittsburgh, Pa. This technology is more fully described in the following U.S. patent applications, hereby incorporated by reference in their entireties: U.S. patent application Ser. No. 11/450,138, filed on Jun. 9, 2006, entitled “Forensic Integrated Search Technology”; U.S. patent application Ser. No. 12/017,445, filed on Jan. 22, 2008, entitled “Forensic Integrated Search Technology with Instrument Weight Factor Determination”; and U.S. patent application Ser. No. 12/339,805, filed on Dec. 19, 2008, entitled “Detection of Pathogenic Microorganisms Using Fused Sensor Data.”

The present disclosure may be embodied in other specific forms without departing from the spirit or essential attributes of the disclosure. Accordingly, reference should be made to the appended claims, rather than the foregoing specification, as indicating the scope of the disclosure. Although the foregoing description is directed to the embodiments of the disclosure, it is noted that other variations and modification will be apparent to those skilled in the art, and may be made without departing from the spirit or scope of the disclosure.

Claims

1. A system comprising: a first illumination source configured to illuminate a target, wherein said target comprises an unknown material, to thereby generate a plurality of interacted photons;a collection optics for collecting said plurality of interacted photons;a spectral encoding device for assessing said plurality of interacted photons; anda first imaging device configured so as to detect said plurality if interacted photons and generate at least one of: a MWIR hyperspectral image representative of said target, a SWIR hyperspectral image representative of said target, and combinations thereof.

2. The system of claim 1 wherein said first illumination source comprises an active illumination source.

3. The system of claim 2 wherein said active illumination source comprises a broadband light source.

4. The system of claim 1 wherein said first illumination source comprises a passive illumination source.

5. The system of claim 4 wherein said passive illumination source comprises a solar illumination source.

6. The system of claim 1 wherein said first illumination source comprises an active broadband illumination source, and further comprising, a second illumination source wherein said second illumination source comprises a passive solar illumination source.

7. The system of claim 1 wherein said collection optics comprises at least one optic selected from the group consisting of: a telescope optic, a fixed optic, a zoom optic, a combination optic, and combinations thereof.

8. The system of claim 1 wherein said first imaging device comprises at least one of: a InGaAs detector, an InGaAs extended range detector, a InSb detector, a PtSi detector, and combinations thereof.

9. The system of claim 1 further comprising a second imaging detector configured so as to generate a video image representative of an area of interest, wherein said area of interest comprises said target.

10. The system of claim 9 wherein said second imaging detector comprises a RGB video imaging device.

11. The system of claim 1 wherein said spectral encoding device is selected from the group consisting of: a fixed filter, a multivariate optical element, a Fabry-Perot filter, and combinations thereof.

12. The system of claim 1 further comprising a means for assessing at least one of said MWIR hyperspectral image, said SWIR hyperspectral image, and combinations thereof, to thereby identify said unknown material as at least one of: an explosive agent and a non-explosive agent.

13. The system of claim 9 further comprising a means for assessing said video image representative of said area of interest to thereby identify a target.

14. A method comprising: illuminating a target, wherein said target comprises an unknown material, to thereby generate a plurality of interacted photons;assessing said plurality of interacted photons using a spectral encoding device;detecting said plurality of interacted photons using a first imaging detector to thereby generate at least one hyperspectral image representative of said target, wherein said hyperspectral image comprises at least one of: a MWIR hyperspectral image representative, a SWIR hyperspectral image, and combinations thereof; andassessing said at least one hyperspectral image to thereby identify said unknown material as at least one of: an explosive agent and a non-explosive agent.

15. The method of claim 14 wherein said illuminating comprises at least one of: actively illuminating said target, passively illuminating said target, and combinations thereof.

16. The method of claim 14 wherein said spectral encoding device comprises at least one of: a Fabry-Perot filter, a fixed filter, a multivariate optical element, and combinations thereof.

17. The method of claim 14 wherein said first imaging detector comprises a detector selected from the group consisting of: a InGaAs detector, an InGaAs extended range detector, a InSb detector, a PtSi detector, and combinations thereof.

18. The method of claim 14 further comprising generating a RGB video image representative of an area of interest, wherein said area of interest comprises said target.

19. The method of claim 18 further comprising assessing said RGB video image to thereby identify said target.

20. The method of claim 14 wherein said assessing is achieved by applying at least one algorithm selected from the group consisting of: object imaging and tracking, image weighted Bayesian fusion, simultaneous location and mapping, scale-invariant feature transform, hybrid false color, and combinations thereof.

21. The method of claim 14 wherein said assessing is achieve by applying at least one chemometric technique.

22. The method of claim 18 further comprising fusing at least two of the following: said MWIR hyperspectral image, said SWIR hyperspectral image, said RGB video image, and combinations thereof.