homeland security technology council
TRANSCRIPT
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Department of Physics
TERAHERTZ IMAGING and DETECTION OF
SUICIDE BOMBERS*
J. F. Federici, D. Gary, B. Schulkin, F. Huang, H. AltanDepartment of Physics
R. Barat
Department of Chemical Engineering
K. Walsh
Picatinny Arsenal
*Funded by US Army and NSF
http://physics.njit.edu/~federici
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Outline
THz Basics
Basics of Interferometric Imaging
Spectral Information
Spatial information
Simulated Images
cm resolution at 100m distances
Spectral Resolution of Explosives and Metals
Analysis of Images
Current and Future Work
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Department of Physics
What is Terahertz (THz)?
1 THz frequency = 300 m wavelengthor 33 cm-1 or 4.1 meV or T = 48 K
Radio Microwave T-rays Infrared UV X-rays
Frequency (Hz)
108 109 1010 1011 1012 1013 1014 1015 1016 101
Visible
Also known as Far-Infrared or sub-millimeter
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THz at NJIT
1997-2001 Developed various THz sources, detectors, andimaging techniques
Two PhD students graduated, 9+ publications in THz
technology
2000-2001 Developed concept for Detection of explosives,
chemical and biological weapons using new THz imaging
methodology.
Spring 2001 - Proposal for cargo screening submitted to FAA
Post 9/11 - National Science Foundation and US Army Funding
8 publications since 2002, 2 patents pending
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Wide Area Surveillance
NJIT Team is developing THz imaging techniques for Stand-Off
Detection of concealed Explosives, Chemical/Biological Agents
Development of Technique/ Hardware for Imaging
Development of Image Analysis
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Comparison with Other Techniques
X-Ray, Neutron Scattering - Uses high energy radiation
damages biological systems - eg. damages DNA/ tissues
permissible exposure limited - more difficult for use on
people.
THz - low energy radiation - non-ionizing
no damage to biological tissue
differentiation of target compounds based on THz color
Imaging and color information combination will reduce
false alarm rate.
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Disadvantages of THz for Scanning
for Explosives / BioAgents
Metals are opaque to THz
will reflect the THz
THz strongly absorbed by water
will not detect explosives inside the body
THz scanners will likely be used in
conjunction with other detection techniques.
Nota forensic technique - looking for 1cm2
size blocks of material
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Department of Physics
Application of High-Resolution X-Ray Raman Scattering to Homeland Security
T. A. Tyson, Q. Qian (NJIT), Z. Zhong, C.-C. Kao and W. Caliebe (NSLS)
X-ray absorption spectroscopy of is onemethod that can be used to identify chemical
systems by threshold spectra. The resonance
features in x-ray absorption spectra are
uniquely related with the molecular
structure enabling rapid chemical
identification.
Utilizing 100 KeV x-rays with highpenetration power and a transmission x-ray
analyzer system based on a working design
(left), we will develop a system for
detecting explosives and chemical
weapons by fingerprinting their spectra.
260 280 300 320 340 360
0.75
0.80
0.85
0.90
0.95
1.00
Inten
sity
Energy(eV)
Carbon K-Edge of Graphite (X-Ray Raman)
The upper and lower left panels show the full spectrometerand blow up of the analyzer array, respectively. Each of the
nine x-ray focusing mirrors can be independently aligned
with micro radian precision in the horizontal and vertical
planes. The lower left panel show the carbon K-edge
spectrum of graphite measured in energy loss mode (x-ray
Raman spectrum) with a resolution of ~ 0.5 eV.
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Advantages of THz for Scanning
for Explosives / Bio and Chemical Agents
THz transmits through most non-metallic materials:plastic, paper , clothing
THz yields transmission / reflection spectra of targets*
ExplosivesKemp (2003)
Transmissive Bas.Sub. Spectra
Woolard et al (2003)
* See papers fromProc. SPIE5070, (2003)
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Interferometric Imaging - Motivation
Therefore
To image in the THz, one must generate images using only a few to a few
hundred detector elements.
Possible Solution: Interferometric imaging
A THz digital camera would be ideal for THz imaging:However
consumer digital cameras imaging arrays of 1024 by 768 pixels or 780,000
individual detector elements in the array.
That high density of detectors in THz range not technologically possible.
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Sample Array Geometry
)1(
n
obrad
Detector Distance
to Origin:
Exponential Distances Ensure Non-
redundant Spacing of Detector Pairs
66 detector pair combinationsRotation of 90o with data acquired every 1o:
66*90 = 5940 points in u-v plane
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Estimated Angular Resolution
b (meters)10 1 0.1 0.01 0.001
0.1 62" 10' 1.7o 17o 170o
1.0 6.2" 62" 10' 1.7o 17o
(THz)
10.0 0.6" 6.2" 62" 10' 1.7o
Field-of-View determined by either Field-of-View of individualDetectors or Bandwidth of Detectors.
Angular (Spatial) Resolution determined by spacing between
Detector Pairs.
A 1m baseline array has a spatial resolution of 3cm at 100m!
Scaling down to cargo unit or hand-held size of smoke detector!
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Department of Physics
Simulation of THz Imaging Array
Detection of RDX and Metal at
a distance of 30m
Objects 1.5cm in size
Composite Image combination ofTHz images taken at 5 different
frequencies
Spectral and Spatial Images
Objects with spectral content of
RDX colored Red
Objects reflecting all THz radiation
colored white
RDX Metal
Sidelobes
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Focusing of Image
ImagingArray
Object
Focal Length
Single frequency, uncleaned image
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Image Analysis - Neural Networks
U
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U M M M M M S A A U F F F A
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BLUE = metal coin
PINK= bioagent
GREEN = flour
ORANGE = starch
THz Image at 1 frequency
Neural Network Analysis
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Present and Future Work
Development of Benchtop model underway todemonstrate key technological components
Detect C4 versus peanut butter hidden in clothing.
Scale up to imaging system for suicide bombers(system size about 1m)
Scale to hand-held/ cargo container unit (10cm size,
battery operated unit)