U.S. patent application number 15/596345 was filed with the patent office on 2017-11-16 for multi-threat detection of moving targets.
The applicant listed for this patent is Valery AVERYANOV, Igor GORSHKOV, Andrey KUZNETSOV. Invention is credited to Valery AVERYANOV, Igor GORSHKOV, Andrey KUZNETSOV.
Application Number | 20170329033 15/596345 |
Document ID | / |
Family ID | 60296999 |
Filed Date | 2017-11-16 |
United States Patent
Application |
20170329033 |
Kind Code |
A1 |
KUZNETSOV; Andrey ; et
al. |
November 16, 2017 |
MULTI-THREAT DETECTION OF MOVING TARGETS
Abstract
The present invention comprises a multi-modal security
checkpoint. The security checkpoint can simultaneously scan for and
simultaneously identify hidden metallics (e.g., weapons, shrapnel)
and non-metallics (e.g., explosives, dielectrics). The security
checkpoint performs scanning and identifying at a rate of 15 or
more frames per second for all targets within the inspection area.
The security checkpoint comprises blocks for sending and receiving
radiation signals, the blocks comprising transmitters and/or
receivers, the blocks being configured to share information to
compare cross- and co-polarizations of signals emitted. The
security checkpoint combines many threat detection technologies
into one checkpoint that allows it to be robust and detect a large
variety of threats in mass transit hubs requiring high throughput
processing capabilities.
Inventors: |
KUZNETSOV; Andrey; (St.
Petersburg, RU) ; AVERYANOV; Valery; (St. Petersburg,
RU) ; GORSHKOV; Igor; (St. Petersburg, RU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
KUZNETSOV; Andrey
AVERYANOV; Valery
GORSHKOV; Igor |
St. Petersburg
St. Petersburg
St. Petersburg |
|
RU
RU
RU |
|
|
Family ID: |
60296999 |
Appl. No.: |
15/596345 |
Filed: |
May 16, 2017 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14964328 |
Dec 9, 2015 |
9697710 |
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15596345 |
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14319222 |
Jun 30, 2014 |
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14964328 |
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14259603 |
Apr 23, 2014 |
9330549 |
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14319222 |
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14160895 |
Jan 22, 2014 |
9282258 |
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14259603 |
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13528412 |
Jun 20, 2012 |
9304190 |
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14160895 |
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62211707 |
Aug 29, 2015 |
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61945921 |
Feb 28, 2014 |
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61905940 |
Nov 19, 2013 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06K 2209/09 20130101;
H04N 5/32 20130101; H04N 7/181 20130101; G06K 9/00771 20130101;
H04N 13/282 20180501; G08B 21/02 20130101; G01V 3/12 20130101; G01V
8/10 20130101; H04N 13/239 20180501; G01V 8/005 20130101; H04N 5/30
20130101 |
International
Class: |
G01V 3/12 20060101
G01V003/12; G08B 21/02 20060101 G08B021/02; G01V 8/00 20060101
G01V008/00; G01V 8/10 20060101 G01V008/10; H04N 13/02 20060101
H04N013/02; H04N 7/18 20060101 H04N007/18 |
Claims
1. A security checkpoint, comprising: at least one first block for
detecting a first threat, the first threat comprising an explosive,
at least one second block for detecting a second threat, the second
threat comprising a metal, a processing unit, said processing unit
performing a scanning of data from all blocks, said processing unit
further determining a presence of a threat comprising an explosive
or a metal weapon, said determining occurring on a frame-by-frame
basis, an alarm, said alarm starting in case of a suspected threat
presence, the alarm differentiating a type of the threat, the type
of the threat being said first threat, said second threat, or a
combination thereof, wherein the first block performs a measurement
of a phase delay of a radiation and an amplitude of a radiation;
wherein the radiation is irradiated by one or more transmitters,
wherein the radiation is received by one or more receivers, wherein
the phase delay and any amplitude changes are caused by two or more
of: (1) the radiation being reflected by a garment, (2) the
radiation travelling through the garment and being reflected by a
human body, and (3) the radiation passing through the garment and
an unknown object and being reflected by the human body, and
wherein said processing unit determines a presence of a threat
comprising an explosive or a metal weapon by comparing
cross-polarized vs. co-polarized amplitudes.
2. (canceled)
3. The security checkpoint of claim 1, wherein said processing unit
further differentiates between a body without threats, a body with
metals, and a body with dielectrics.
4. The security checkpoint of claim 1, further comprising
simultaneous video imaging.
5. The security checkpoint of claim 1, wherein an angle of
inspection is greater than 90 degrees.
6. The security checkpoint of claim 1, wherein a distance between
blocks is at least 2.4 meters.
7. The security checkpoint of claim 1, wherein said scanning and
said determining a presence of a threat comprising an explosive or
a metal weapon occurs simultaneously in real-time.
8. The security checkpoint of claim 7, wherein said determining a
presence of a threat comprising an explosive or a metal weapon
occurs in 50 milliseconds to 2 seconds.
9. The security checkpoint of claim 7, wherein said determining a
presence of a threat comprising an explosive or a metal weapon
occurs within 50 milliseconds.
10. The security checkpoint of claim 1, further comprising a
wideband frequency generator, said wideband frequency generator
being configured to switch a frequency of an emitted radiation
within 4-6 microseconds.
11. The security checkpoint of claim 10, further comprising a
multilayer electronic board, said multilayer electronic board
comprising multiple output fast keys, said multiple output fast
keys having a switching time on an order of tens of
nanoseconds.
12. The security checkpoint of claim 1, wherein 15 or more frames
are captured and processed by said processing unit per second.
13. The security checkpoint of claim 12, wherein 15 or more frames
are captured and processed by said processing unit per second for
all subjects within an inspection area simultaneously.
14. The security checkpoint of claim 13, wherein said subjects
comprise moving objects.
15. The security checkpoint of claim 1, wherein an inspection area
is 3 meters long and 3 meters wide.
16. The security checkpoint of claim 1, wherein an inspection area
is 6 meters long and 3 meters wide.
17. The security checkpoint of claim 1, wherein the first block is
oriented at 90 degrees relative to the second block.
18. The security checkpoint of claim 1, comprising at least two
pillars for receiving said radiation, a first pillar being turned
about its axis of symmetry relative to a second pillar.
19. The security checkpoint of claim 1, wherein said processing
unit further reconstructs two 3D microwave images, comprising a
first 3D microwave image of co-polarizations and a second 3D
microwave image of cross-polarizations.
20. The security checkpoint of claim 19, wherein said processing
unit further correlates corresponding 3D video imaging information.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present patent application is a Continuation-In-Part of
U.S. patent application Ser. No. 14/964,328, filed Dec. 9, 2015,
which claims priority to U.S. Provisional Patent Application Ser.
No. 62/211,707, filed Aug. 29, 2015, and which is a
Continuation-In-Part of U.S. patent application Ser. No.
14/319,222, filed Jun. 30, 2014, which is a Continuation-In-Part of
U.S. patent application Ser. No. 14/259,603, filed Apr. 23, 2014,
now U.S. Pat. No. 9,330,549, which claims priority to U.S.
Provisional Patent Application Ser. No. 61/945,921, filed Feb. 28,
2014, and which is a Continuation-In-Part of U.S. patent
application Ser. No. 14/160,895, filed Jan. 22, 2014, now U.S. Pat.
No. 9,282,258, which claims priority to U.S. Provisional Patent
Application Ser. No. 61/905,940, filed Nov. 19, 2013, and which is
a Continuation-In-Part of U.S. patent application Ser. No.
13/528,412, filed Jun. 20, 2012, now U.S. Pat. No. 9,304,190. The
teachings and disclosure of U.S. Pat. No. 9,282,258, are included
via reference herein in their entireties. All said applications and
their disclosures are incorporated herein by reference in their
entireties.
FIELD OF THE INVENTION
[0002] This invention is in the field of multiple threat detection
systems. Particularly this invention is in the field of detecting
concealed or hidden improvised explosive devices (IEDs), metallic
weapons and/or shrapnel, and radioactive and nuclear materials.
BACKGROUND ART
[0003] The closest threat detection system to present invention is
the Rapiscan Systems Secure 1000 SP. The Secure 1000 SP uses
backscatter technology as well as image processing software and an
operator interface to screen passengers for a wide range of
potential threats including liquids, contraband, ceramics,
explosives, narcotics, concealed currency and weapons. The Secure
1000 SP generates a front and back scan simultaneously. The Secure
1000 SP can detect small objects and threats concealed on a
passenger. It can detect organic and inorganic threats, metals and
non-metallic objects and can detect concealed liquids, ceramics,
weapons, plastic explosives, narcotics, metals, contraband,
currency etc. The Secure 1000 SP requires one pose with no
additional movement by the passenger, a full scan can be completed
in seconds. The Secure 1000 bounces very low dose of x-rays off of
a person to generate an image. This image is then analyzed by an
operator to identify concealed potential threats.
[0004] The Rapiscan Systems Secure 1000 is limited in that it
requires a person to be in a single pose for scanning, it requires
an operator to determine what threats are present and to review the
scanned images, it uses x-rays for scanning, it only performs
backscatter and no pass through imaging, at it is designed to work
at a security checkpoint as opposed to use in an array where it can
scan multiple individuals and their luggage without causing a
security bottleneck. The Rapiscan Systems Secure 1000 is incapable
of detecting radiation/nuclear materials.
[0005] There is a need for multi-threat detection systems with very
short processing time allowing detection of a variety of threats
simultaneously.
SUMMARY OF THE INVENTION
[0006] The present invention uses microwave detection to find
non-metallic objects that are hidden, it uses cross-polarized
microwaves to detect hidden metallic weapons or shrapnel, and uses
gamma ray detection to find radioactive materials. Each of these
technologies provide threat detection, combined these technologies
can provide detection of even more types of threats.
[0007] The present invention using microwave detection used in
conjunction with cross-polarized microwave detection detects IEDs
with shrapnel. When using microwave detection, reflective or pass
through, dirty bombs are detectable. And the combination of cross
polarized microwave detection with gamma detection allows for
detection of radioactive/nuclear material that is shielded by
metal.
[0008] The present invention allows for real time scanning of
individuals, multiple individuals at once, for reflected microwave,
cross polarized microwave, and radioactive/nuclear scanning either
in a security checkpoint or in an open array/portal that people
walk through. The devices in an array/portal can be disguised as
advertisement space, information boards, etc. The present invention
can be used in conjunction with facial recognition software to
track a suspicious individual through a given space. The present
invention can be use with a limited access entry portal that can
isolate an individual to perform subsequent scans in order to
determine, automatically, if a threat is detected or if there is a
false alarm all while minimally disrupting throughput of the entry
portal. The present invention can also be integrated into a system
of multiple scan points and use subject tracking in order to
perform additional scans and automatically determine threat
presence. Furthermore, the invention can be practiced in an
automatic manner or be reviewed by operators. The invention can
also be used to perform pass through and radiation/nuclear scans of
rolling luggage, handbags, briefcases, backpacks, etc. The present
invention also performs automatic facial recognition from a
distance, against a database of known or suspected terrorists and
provide an alert. The present invention provides different alerts
based upon the types of materials found.
[0009] An appreciation of other aims and objectives of the present
invention and a more complete and comprehensive understanding of
this invention may be achieved by referring to the drawings, and by
studying the description of preferred and alternative
embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention will now be discussed in further
detail below with reference to the accompanying figures in
which:
[0011] FIG. 1 provides a schematic block diagram of multi-threat
detection system.
[0012] FIG. 2 shows a detailed schematic of threat detection block
1, the active microwave detection system.
[0013] FIG. 3 shows the microwave path and reflection off a
target's coat and body boundaries (first and second boundaries,
respectively).
[0014] FIG. 4 further details a microwave (MW) beam's reflection in
(a) the absence, and (b), (c), (d) the presence of hidden dangerous
objects. FIG. 3 (b) shows an example of the location of explosives
on the human body under the coat or other garment. FIGS. 3(c) and
3(d) show the optical paths and distances measured or calculated by
the claimed invention in the case of hidden objects.
[0015] FIG. 5 detectors in the cross-polarization method of the
present invention.
[0016] FIG. 6 is a schematic image of hidden metal threat obtained
via the cross-polarization method of the present invention.
[0017] FIG. 7 is a schematic block diagram of the nuclear material
detection block 3.
[0018] FIG. 8 shows a spectrum of cesium-137 obtained by sodium
iodide (NaI) detector (prior art).
[0019] FIG. 9 shows a graphical example of transmitters with a
wide-angle radiation pattern 91 in polar coordinates, at a
frequency of 11 GHz. The main lobe is 90.7 degrees at 3 dB
beamwidth 92.
[0020] FIG. 10 shows a graphical example of receivers with a
wide-angle radiation pattern 101 in polar coordinates, at a
frequency of 10 GHz. The main lobe is 90 degrees at 3 dB beamwidth
102.
[0021] FIG. 11 shows an example illustration of a wide angle of
inspection greater than 90 degrees of an inspected area
(transmitters and receivers are located on each of the left and
right pillars).
[0022] FIG. 12 shows an example illustration of a wide zone of
inspection and operating pillars as a single system and as a
complex system. A single system according to the present invention
comprises means for transmitting and receiving wherein both means
are located on one pillar or block. A complex system according to
the present invention comprise means for transmitting and receiving
wherein the transmitting means and receiving means are located on
two or more separate pillars which may further correspond with each
other.
[0023] FIG. 13 shows an example flowchart illustration of the
real-time processing (greater than 15 frames per second) of signals
received and the fast switching, according to the present
invention. In FIG. 13, each bold line represents different levels
of processing as related to the fast switching. The total time
estimated for each specific switching is exemplified in the figure;
for example, the lowest bold line represents a process of switching
between individual transmitting antennas in an array of
transmitters and the time required, according to the present
invention, for information (statistic/data) collection by an
individual transmitter (occurring in the order of 10.sup.-7
seconds). Summing all transmitter (Tx) switching, and combining all
frequencies into one frame, the result in this particular example
is at least 15 frames per second.
[0024] FIGS. 14A-14B. FIG. 14A shows a graph of cross-polarized vs.
co-polarized amplitudes for (1, square points) a body without
objects, (2, circular points) metals on a body (shrapnel and a
gun), and (3, triangular points)) a dielectric on a body (wax).
FIG. 14B shows a graph representing discrimination between a body
without objects 41, a body with metals 42, and a body with
dielectrics 43, obtained by employing an SVN algorithm with
Principal Component Analysis (PCA) data pre-processing. FIG. 14A
represents experimental data collected in Cross- and Co-polarized
amplitudes. FIG. 14B represents the same data as in FIG. 14A but
after pre-processing in the PCA algorithm, and in coordinates of
the two main principal components 1 and 2. The PCA processing
removes the influence of measurement units in raw data and can also
removes noise components from raw data (e.g., when more than 2
"row" parameters are used). FIG. 14B represents, in particular
regions, how to differentiate data for three different cases (even
if some of points are very close to one another): body without
objects 41, a body with metals 42, and a body with dielectrics 43.
The Principal Component Analysis (PCA) algorithm used for
pre-processing, as exemplified in FIG. 14B allows for
differentiation of, e.g., row data which partly overlap, as
exemplified in FIG. 14A. After the PCA processing, an appropriate
classification algorithm can be used, such as, e.g., support vector
machines or one of the following: Bayes classifier, neural
networks, gradient boosted trees, K-nearest values, etc.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0025] As radio waves travel through the air, they travel in a way
similar to waves of water moving across the surface of the ocean.
The shape of a simple radio signal can be depicted as a repeated up
and down movement or vibration. This up and down motion of the wave
takes place in three dimensions. A wave which is polarized parallel
to the plane of propagation is called a horizontally polarized
wave. A wave which is polarized perpendicular to the plane of
propagation is called a vertically polarized wave. The height or
intensity of the wave is called the amplitude of the wave. The idea
of polarization is applicable to all forms of transverse
electromagnetic waves, whether they are radio waves at microwave
frequencies, or light waves such as those emitted by a
flashlight.
[0026] The power levels radiated by the present invention are much
lower than conventional radar systems or than those generated by
x-ray or other imaging systems that are currently employed to
detect objects at the entry of an airport or a courtroom. In
general, some of the preferred embodiments of the invention operate
in the MHz or GHz frequency bands. Different radio or microwave
frequencies offer different benefits and disadvantages for the
object detection provided by the present invention. Although the
description of some embodiments of the invention include specific
references to particular frequency ranges, the system may be
beneficially implemented using a wide variety of electromagnetic
radiation bands.
[0027] FIG. 1 presents a schematic block diagram of the system: a
block 1 detecting a first threat, which is explosives or improvised
explosive device (IED); a block 2 detecting a second threat which
is metal weapon; and block 3 detecting a third threat 3 which is
radioactive and nuclear material. Those blocks share certain
sensors or other elements to obtain data related to all threats
thus creating an interleaved united system. All data from all three
blocks enters a processing unit 5, where it is processed
simultaneously. The results of the processing are visualized in
computer 6. The computer 6 is connected to alarm system 7 to
provide audio and/or visual alarm in the case of potential threat.
The alarm has an ability to indicate what type of threat is
detected.
[0028] To facilitate the detection, in one embodiment, the system
also includes a face recognition unit 4 (FIG. 1), which compares a
checked person face with images of faces from a database of known
members of terrorist organizations.
[0029] Below we disclose various embodiments of the blocks 1-4
below and the ways they are interconnected. In the following
description, for purposes of explanation, specific examples are set
forth to provide a thorough understanding of the present invention.
However, it will be apparent to one skilled in the art that these
specific details are not required in order to practice the present
invention. The same techniques can easily be applied to other types
similar systems.
[0030] Block 1
[0031] Block 1 makes it possible to remotely determine the
dielectric permittivity of a moving, irregularly-shaped dielectric
object. The dielectric permittivity of a dielectric object is
determined when the object is placed against the background of a
reflector. The method includes recording a 3D microwave and a 3D
optical range images of an interrogated scene at the same time
moment, digitizing all images and overlapping them in one common
coordinate system; determining a space between the microwave and
optical image (as described below), calculating a dielectric
permittivity c of the space; and concluding the absence of hidden
dielectric object where the dielectric permittivity is less than a
threshold value. If the dielectric permittivity is in the fixed
range (for example 2.9-3.1), then the conclusion is made on the
presence of a hidden object.
[0032] FIG. 2 shows the schematics of the first block 1 for Active
Microwave Detection (AMD). The interrogated space is digitally
scanned with microwave radiation using two or more elemental
microwave emitters 10. The signal reflected from the monitored area
is picked up by one or more parallel microwave detectors 8A and 8B.
The received signal undergoes coherent processing in digital signal
processing unit (DSP) 5 to obtain maximum intensity values of the
restored configuration of scattering objects in the monitored area,
depending on the distance from the elemental emitters to the
target. The information obtained after processing is then displayed
on the computer 6 by constructing a microwave image corresponding
to a three-dimensional surface. A video image of the target is also
obtained using two or more video cameras 9A and 9B which are
synchronized with the microwave emitters 10 via the processing unit
5. The obtained video images are transmitted into the processing
unit and are further converted to its digital form, and a
three-dimensional image of the target is constructed and displayed
on the display 6.
[0033] The AMD operates by sending microwaves (in centimeters
range) towards a moving target (e.g., a person), and detecting the
reflected waves afterwards. The data analysis is carried out in
real time by high-speed GPUs to obtain the image of a potentially
hidden object and receive information about its volume and
dielectric properties, which allows distinguishing between a common
object and a potential explosive. This information is then used to
automatically assign a threat level to the found `anomaly` without
an operator's involvement.
[0034] A system for unveiling a dielectric object in an
interrogated space is disclosed, wherein the interrogated space is
located between an inner layer and an outer layer, comprising at
least two microwave (MW) sources and at least one MW receiver
forming 3D MW images of the interrogated space, wherein said 3D
microwave images are formed by emitting MW signals from the MW
sources towards the interrogated space, wherein each MW signal
partially reflects off the outer layer (first boundary in FIG. 3)
and the remainder of the MW signals travels through the
intermediary space, where the reminder of the MW signals partially
reflects off the inner layer (second boundary in FIG. 3), where
said MW receiver receives reflected signals from said outer and
inner layer, further comprising a computer/calculator which is
adapted for determining at least two distances P1 and P2, between
at least two sets of points, where P1=(A2-A1) and P2=(B2-B1);
wherein A1 is a point of a first MW beam reflected from the outer
layer, and A2 is a point of the same first MW beam reflected from
the inner layer, wherein B1 is the point of a second MW beam
reflected from the outer layer, and B2 is a point of the same
second MW beam reflected from the inner layer (FIG. 4 a and c),
wherein the at least two sets of two points are spaced from each
other by a predetermined value S; and which is further adapted for
calculating the difference D between P1 and P2 and comparing the
difference D with a predetermined threshold value T; and further
comprising an alarm adapted for indicating a likelihood of a hidden
dielectric object between the inner and the outer layer, if the
difference between P1 and P2 is greater than a threshold value
T.
[0035] Also, a method for unveiling hidden objects in an
intermediary space is disclosed, wherein the intermediary space is
located between an inner layer and an outer layer, comprising
sending microwave (MW) signals from MW sources towards the
interrogated space, the signals being partially reflected on the
outer layer and partially on the inner layer, receiving at a MW
receiver a first and a second response of MW signals reflected back
from the outer and the inner layer; the first and the second
response signals corresponding to a first and a second 3D MW image,
wherein the first 3D MW image corresponds to the outer layer of the
interrogated space, and the second 3D MW image corresponds to the
inner layer of the interrogated space, determining at least two
distances, P1 and P2, where P1=(A2-A1) and P2=(B2-B1); where A1 is
a point of a first MW beam reflecting from the outer layer and A2
is a point of the same first MW beam reflecting from the inner
layer, where B1 is the point of a second MW beam reflecting from
the outer layer and B2 is a point of the same second MW beam
reflecting from the inner layer; wherein A1 and B1 are spaced from
each other by a predetermined value S; calculating the difference D
between P1 and P2, comparing the difference D with a predetermined
threshold value T; indicating if the difference D is greater than
the threshold value T. In one embodiment, the method further
comprises determining at least a third and a fourth distance P3 and
P4 from a third and a fourth response signal, where P3=(C2-C1) and
P4=(D2-D1), where C1 is the point of a third MW beam reflecting
from the outer layer and C2 is a point of the same third beam
reflecting from the inner layer, where D1 is a point of the fourth
MW beam reflecting from the outer layer, and D2 is a point of the
same fourth MW beam reflecting from the inner layer. P3 and P4 can
be used to increase reliability of an alarm triggered when the
difference D between P1 and P2 is greater than the threshold value
T. P3 and P4 can be determined in essentially the same area where
P1 and P2 are determined, but using different viewing angels. P3
and P4 can also be used to detect further hidden objects in a
different area than where P1 and P2 are determined.
[0036] The interrogated space can be between the body of a person
and the clothing of this person or between two layers of clothing
of a person. The outer layer is preferably formed by the boundary
between air and the outer clothing of a person.
[0037] 3D Microwave Imaging.
[0038] Determining the presence of a potentially hazardous object
carried by a target 11 is done in the following manner (FIG. 3).
Some of the primary emitted MW radiation 12 is partially reflected
by the first (outer) boundary (usually the person's
coat/jacket/outer garment) forming a reflected beam 13 (see FIG.
4(a)--an enlarged view of area N--for greater detail). The same
radiation/wave then travels through the coat until reflected by the
second (inner) boundary, the human body, forming a second reflected
beam 14. Thus, at least two reflections of the same wave occur--one
reflection occurs at the outer boundary of the target and/or object
(i.e. the first border, or air/intermediary space border) and
another reflection occurs after the wave travels through the
intermediary space and reflects off the target's body (i.e. the
opposite side of the hidden dielectric object, if present). The
measured distance P1 of the intermediary space between the first
and second boundaries is recorded and used to detect the presence
of hidden objects, P1=(A2-A1) is the distance between the point A2
on the second boundary and corresponding point A1 on the first
boundary. This process is repeated for measuring of at least one
other distance or continuously for measuring of other distances,
allowing microwave beams to hit and reflect off of various
locations along the first and second boundaries. Each additional
microwave beam that reflects off additional locations along the
first and second boundaries B1, C1, D1, . . . and B2, C2, D2, . . .
allows for measurement of additional distances P2, P3, P4, . . .
between first and second boundaries. With microwave signals being
emitted and received continuously, 3D microwave images of the
inspected area are created. The first 3D MW image corresponds to
the first boundary, and the second 3D MW image corresponds to the
second boundary. The method allows determining the presence of
hidden dielectric objects on the human body under the outer garment
or carried by the person. Area N is enlarged and shown in greater
detail in FIG. 4(a). FIG. 4(a) represents a situation without a
hidden object. FIG. 4(b) illustrates how an explosive might be worn
on the body under a coat. In a preferred embodiment of the present
invention, the hidden objects are explosive materials of components
thereof. In one embodiment, the method of the present invention is
used to unveil hidden suicide bombs in a crowd of moving people.
The dielectric constant of explosives is about three or larger. The
MW radiation traveling through a medium with such a high dielectric
constant is equivalent to traveling a longer distance in air and
thus the microwave image of a hidden object is portrayed as a
cavity protruding into the body, as illustrated by FIG. 4(c). This
seemingly longer distance corresponds to a sharp change of the
microwave beam path length, which is detected by the receivers
because the MW beam in a first area 15 contains extra path gain
compared to the MW beam in a second area 16. By measuring the phase
and amplitude of incoming reflected microwaves, the microwave path
(i.e. the path of the microwave beam/signal) can be determined and
the sudden sharp change of the path in certain areas, if present,
is registered. Because a microwave travels more slowly in an object
with a higher dielectric (permittivity) constant, a second border
signal takes longer to arrive in the presence or area of an object
(compared to areas where no object is present, e.g., just above,
below, or to either side of an object.). If the change in path
value exceeds a preset threshold value, it serves as an indication
that a hidden object is present.
[0039] In the preferred embodiment, the threshold value T is system
resolution in depth in the direction perpendicular to the first and
the second boundaries (i.e. the outer and inner layers, also called
borders). In the preferred embodiment, the resolution is equal to 1
cm. The resolution depends on the bandwidth of the MW frequencies
used. The resolution is equal to the speed of light in vacuum
divided by the doubled bandwidth of the MW frequencies used.
Bandwidth of the MW frequencies is typical 15 GHz, which thus means
1 cm resolution in depth.
[0040] The additional path, h (see FIG. 4(d)), is equal to
h=l((.di-elect cons..sup.1/2-1)/(.di-elect cons..sup.1/2)), where l
is the thickness of the intermediary space, which equals the
distance from the first boundary to the second boundary including
the cavity, if present, as shown by the first area 15 (see FIG.
4(c)), and is the dielectric (permittivity) constant of the
intermediate space. The additional path, h, is calculated by
subtracting the measured value of the second area 16 from the
measured value of the first area 15.
[0041] The first and the second border signals can be used to
reconstruct two 3D MW images of a person, one corresponding to the
outer garment and the other corresponding to the human body, as
described above. However, the signal received from the first border
of an interrogated space, due to its small value, may be disrupted
by the side lobes (i.e. secondary maximums) of the signal from the
second border. Preferably, a synchronized video image border can
additionally be used, if the signal/noise ratio is low (see FIG.
2).
[0042] MW radiation can be emitted from various different angles
and the reflected radiation, also travelling from various different
angles, is similarly processed, allowing for accumulation of
additional data to improve the accuracy and resolution of the image
and detection process. Various configurations of setups are
possible.
[0043] Simultaneous 3D Video and MW Imaging.
[0044] Additionally, a 3D video image of the target can be recorded
at the same time of a MW image. In this preferred embodiment, the
method of the invention thus further comprises forming a 3D optical
image of the outer layer of the interrogated space, synchronizing
the 3D optical image with the location of the points A1, B1 and
optionally C1 and D1, determining points A1', B1' and optionally
C1' and D1' on the 3D optical image corresponding to the points A1,
B1 and optionally C1 and D1, calculating the differences
P1'=(A2-A1'), P2'=(B2-B1') and optionally P3'=(C2-C1') and
P4'=(D2-D1') and comparing the values P1 with P1', P2 with P2' and
optionally P3 with P3' and P4 with P4'. Similarly, in the invention
a system as described before is preferred which further comprises
at least two cameras recording optical images of the interrogated
space and being adapted for forming a 3D optical image of the
interrogated space; and a computer which is adapted for
synchronizing in time and superimposition and digital space of the
3D optical image with the 3D MW image formed by the at least two
microwave sources and at least one microwave receiver of the
interrogated space, which is reflected from the outer layer. The
reflection signal from the outer layer (points A1 and B1) may be
few times weaker compared to the reflected signal from the inner
layer (points A2 and B2). Points (A1', B1') from the outer layer
extracted from a 3D optical image of the outer layer of the
interrogated space (delivered by stereo cameras) can be used to
calculate P1' and P2' and compare with P1 and P2.
[0045] Preferably, more than 100 microwave sources are used in the
method of the present invention. It is also preferable to use
microwave sources which have a spectrum comprising multiple
frequencies.
[0046] Preferably, at least two video cameras 9A and 9B (see FIG.
2) record images of the target, and the DSP unit 5 reconstructs a
3D video image of the object. Optical beams do not penetrate the
outer boundary (i.e., the person's outer garment in the example
herein). This 3D video imaging is synchronized in time with the 3D
microwave imaging. Overlapping the 3D video image over the 3D MW
image of the outer border can achieve improved accuracy of the
position of the outer border and improved calculation of the
additional path, h. In one embodiment, the system is additionally
equipped with an automatic alarm, which triggers a sound or a
visual alert if the distance h is above a predetermined threshold
value and thus the presence of a hidden object(s) is suspected.
[0047] In one embodiment the 3D microwave image is formed by
illumination of the scene by microwave radiation from one emitter
and recording the scene image by at least two microwave detectors.
In another embodiment the illumination is performed by at least two
separate microwave emitters that illuminate the scene from
different angles, and the recording is performed by one microwave
detector.
[0048] In one embodiment the microwave emitter radiation is a
coherent microwave radiation at N frequencies, which optionally can
be equi-frequencies, are not related to the lines of absorption of
the irradiated media.
[0049] The 3D optical image is formed by illumination of the scene
by optical radiation and recording the scene image by at least two
optical detectors. Different types of processing may apply. In the
preferred embodiment, a digital signal processor (DSP) performs a
coherent processing, which calculates the 3D image taking into
account both amplitude and phase information of electromagnetic
fields reflected from the interrogated scene.
[0050] Block 2
[0051] The purpose of Block 2 is to detect hidden metal weapon and
metallic shrapnel. When the present invention is used to detect an
object like a handgun, the detection is more easily accomplished
when the handgun is oriented in a way that presents a relatively
larger radar cross section to the detector. For example, a gun that
is tucked behind a person's belt buckle so that the side of the gun
is flat against the waist presents a larger radar cross section
than a weapon holstered on the hip with the gun barrel pointing
toward the ground and the grip pointing forward or back. In
general, the present invention relies on the physical phenomenon of
reflection in which an incident beam of horizontal polarization
will be partially reflected back as vertical polarization. The
percentage of energy converted to vertical polarization depends on
the shape of the weapon in the plane normal to the direction of
incidence and sharpness (contrary to flat parts) of different parts
of weapon (or shrapnel). If the weapon has a cross sectional shape
that has both vertical and horizontal components, then a vertically
polarized component will be realized even though the object is
irradiated by horizontal polarization.
[0052] Measuring the phase of the polarized waves reflected from a
person who may be carrying a concealed weapon is important because
the polarized waves reflected from a concealed weapon and the
polarized waves reflected from a human body behave quite
differently. In general, the reflections from a concealed weapon,
while not constant, vary within a relatively confined range. In
contrast, the reflections from a human body are chaotic. A
preferred embodiment of the invention exploits this generalized
phenomena by using signal processing methods to distinguish the
relatively well-behaved signals from a concealed weapon from the
generally unpredictable signals from a human body.
[0053] The present invention incorporates the apparatus depicted in
FIG. 2 to measure amplitude and phase of the returned cross-pole
signal. Microwave receivers 8A and 8B include two detectors each as
shown in FIG. 5. Detectors 31 and 32 register received microwave
radiation with vertical polarization and detectors 32 and 34--with
horizontal polarization. In one embodiment this is achieved by
placing corresponding polarization filters in front of the
receivers. Data from the detectors 31-34 enters processing
component 35, which is a part of the processing unit 5.
[0054] The present invention reconstructs a 3D MW image and
compares amplitudes of reflected co- and cross-polarization waves
in many places/zones of the human body simultaneously and in real
time. This allows for detection of concealed weapons, shrapnel, or
other items without comparison to pre-stored reference data. In an
alternative embodiment of the invention the present invention takes
reading of multiple individuals and automatically determines the
presence of hidden weapons, shrapnel, or other items
simultaneously.
[0055] The cross-polarization method partially uses the same
equipment (microwave detectors, processing unit, computer, alarm
system) as previously described 3D microwave imaging (Block 1) for
detection of hidden plastic explosives.
[0056] Block 3
[0057] Block 3 uses gamma ray detection to find radioactive
materials. In the preferred embodiment a spectroscopic device for
detecting radioactive and nuclear material is used, which provides
an energy spectra of gamma-ray sources detected, thus allowing to
eliminate naturally occurring radioactive materials (NORM) and
reduce false alarm.
[0058] FIG. 7 shows a schematic of hidden radioactive (and nuclear)
material detection system according to the present invention. A
gamma ray detector 42 fed by a high voltage power supply 41
receives radiation from a source of radioactive radiation hidden in
a personal luggage 43. The data from the detectors 42 enters
multichannel analyzer 44, which is a part of the processing unit
5.
[0059] In the preferred embodiment scintillation detector is used
as gamma ray detector 42. Scintillation detectors use crystals that
emit light when gamma rays interact with the atoms in the crystals.
The intensity of the light produced is proportional to the energy
deposited in the crystal by the gamma ray. The detectors are joined
to photomultipliers that convert the light into electrons and then
amplify the electrical signal provided by those electrons. Common
scintillators include thallium-doped sodium iodide (NaI(T1))--often
simplified to sodium iodide (NaI) detectors--and bismuth germanate
oxide (BGO). Because photomultipliers are also sensitive to ambient
light, scintillators are encased in light-tight coverings. FIG. 8
shows a spectrum of cesium-137 obtained by sodium iodide (NaI)
detector (prior art). The figure shows the number of counts (within
the measuring period) versus channel number (related to energy of
gamma rays).
[0060] Radioactive materials are stored inside sealed metal
capsules (preferably heavy metal, like lead). Cross-polarization
method (Block 2) is designed for detection of metal objects. The
processing unit combines data from the multichannel analyzer 44 and
the processing component 35 (FIG. 7) to increase the reliability of
the radioactive (and nuclear material) detection.
[0061] Block 4
[0062] Block 4 provides face recognition based on comparing the
face image obtained by cameras 9A and 9B (also used in Block 1)
with a database of known suspicious people. Any know technique can
be used for the data processing. For example, U.S. Pat. No.
6,301,370 discloses an image processing technique based on model
graphs and bunch graphs that efficiently represent image features
as jets. The jets are composed of wavelet transforms and are
processed at nodes or landmark locations on an image corresponding
to readily identifiable features.
[0063] Parallel Data Processing Occurring on One or More Computer
Processors.
[0064] The combinatorial processing of data collected by Blocks 1,
2, 3 and/or 4 is unique and advantageous. Such parallel and
combined processing provides simultaneous collection and analysis
of various data from combined threat detection techniques in real
time for check points in public places such as airports, subway,
etc. By processing such data in parallel, rather that separately,
the processing time is greatly reduced, allowing for higher traffic
flow without losing efficiency or quality of the threat detection,
and in some embodiments, further improving the same while also
allowing for higher traffic flow through the system.
[0065] Wide Angle of Inspection.
[0066] The present invention is capable of achieving a wide angle
of inspection, i.e. greater than 90 degrees perspective of an
inspected area. This wide angle is achieved by an antenna design
(emitters, Tx, and receivers, Rx) having a wide directionality
range (more than 90 degrees). Tx and Rx antennas are designed as
directional antennas with a wide antenna pattern with a main lobe
more than 90 degrees at 3 dB beamwidth. See FIGS. 9-11.
[0067] Wide Zone of Inspection.
[0068] The present invention achieves a wide zone of inspection.
The wide zone of inspection is achieved by the following features:
(1) a wide distance between pillars comprising microwave
emitters/receivers (e.g., 2.4 meters between pillars); (2) each
pillar is capable of operating as a single system (i.e.,
transmitters and receivers in one pillar) and also in combination
as a complex system of pillars (i.e., at least two pillars, each
with transmitters and/or receivers which may correspond with one
another); and (3) inspection of targets from varying angles due to
the geometry/setup of the pillars and cameras. See FIG. 12. FIGS. 9
and 10 further show Tx and Rx antennas which each individually have
a greater than 90-degree lobe. FIG. 11 then shows an exemplary wide
angle of inspection in a chosen geometry of pillars and FIG. 12
shows a wide zone of inspection, defined by Tx and Rx antennas
having wide angles, a wide distance between pillars (e.g., 2.4
meters), and a capability of Tx and Rx antennas being located on
the same pillar(s) (i.e., a simple, or independent, system) or a
capability of Tx antennas being located on one pillar (e.g., left)
and Rx antennas being located on another pillar (e.g., right), or
vise-versa (i.e., a complex system). Such a setup allows for an
inspection of targets from varying angles at the same time.
Furthermore, other geometries are possible with 4 (or more)
pillars. Two portals each may then be separated at 3 meters apart
and facing each other (i.e., "Quadro" geometry), or two portals may
be positioned back to back and facing opposite directions. These
geometries and others are described in U.S. Pat. No. 9,282,258,
which is referenced herein in its entirety.
[0069] Digital Focusing. The present invention is capable of
achieving a digital focusing, rather than a mechanical scanning of
the target area and subject(s). The digital focusing is achieved
via coherent processing of the signals received (i.e., including
both phase and magnitude/amplitude data simultaneously). In the
prior art, such digital focusing is impossible or at least limited
by computing resources for moving targets in wide inspection zones.
For example, current prior art system data scans take a period of
tens of milliseconds, but the data processing and analysis of the
same scan takes a period of at least a few seconds. The present
invention, however, is capable of performing both the scanning and
the processing in real time (i.e., total scanning and processing
occurs preferably in less than 50 milliseconds, or 50-60
milliseconds, depending of numbers of targets simultaneously
investigated in the inspection zone. Scanning and processing occurs
in parallel processors (i.e., the scanning and processing occurs
simultaneously).
[0070] The digital focusing and real time processing discussed
above allow for a high throughput without impeding the flow of
targets through the inspection area, a feature which is required in
mass transit hubs. The real-time operation is a result of, and
includes without limitation, the following features: (1) fast
switching of a frequency inside of a specially designed wideband
frequency generator (a typical time for such fast switching,
alongside a good frequency stability, is in the range of a few,
e.g., 4-6, microseconds) 131; (2) fast switching of individual
antennas within an array by specially designed multilayer
electronic boards coupled with (i.e., comprising) multiple output
fast keys (a typical time for such fast switching is in the range
of tens of nanoseconds, e.g., 50-100 nanoseconds). It is further
noted that the fast keys are switched based on an input signal to
one of a set of outputs by command (e.g., four outputs). Four such
keys are designed in a multiplexer (i.e., one input to one of 16
outputs by command). Each fast key (e.g., single microchip) thus
has one input and four outputs. The boards for one antenna array
may thus be 256 individual transmitters, which contains 64 fast
keys to deliver one base signal, in each frequency, to the
individual transmitters in real time; (3) an algorithm designed to
process the signals received as a result of the fast switching
described above, the algorithm being programmed on a microchip
located on an electronic board and controlled by main processor
located within the pillars according to the present invention. See
FIG. 13.
[0071] Discussing FIG. 13 further: One frame of processing may be
broken down as shown in the figure. Moving from the bottom of FIG.
13 upwards, 135 represents the order of time necessary to measure a
reflected signal from one transmitter (Tx) at one frequency (this
occurs on the order of 10' seconds), for example, 800 nanoseconds;
134 represents the total time of all transmitter switching and
signal measurements of all transmitters at one frequency (this
occurs on the order of 10.sup.-5 seconds, as several microwave
signals are measured); 133 represents the order of time necessary
to measure reflected signals from all transmitters at one frequency
(this occurs on the order of 10.sup.-4 seconds); 132 represents the
total time for all transmitter switching at all frequencies
combined and signal measurements of all transmitters at all
frequencies combined (this occurs on the order of 10.sup.-2
seconds); 131 represents the number of frames per second (e.g., 15
fps) produced via a microwave signal measurement in one frame and
within time period of about 50-60 milliseconds.
[0072] Real-Time Processing of Signals Received.
[0073] An important parameter for determining the quality and
efficiency of multi-threat detection is the time in which it takes
to collect one frame of data. A typical time for collecting one
frame is about tens of milliseconds, which includes all targets in
a wide zone with fast frequency switching (typically more than
hundred frequencies) and with fast switching of individual antennas
in the array (typically, more than one thousand individual
transmitters/receivers in up to four antenna arrays). The present
invention is capable of capturing 15 or more frames per second of
all detected targets within the inspection zone simultaneously
(i.e. one frame is collected in about 50 milliseconds, processing
of the same frame takes also about 50 milliseconds in parallel to
the collection time; therefore, the two values determine a value of
15 frames per second, or more if one of the two values is further
shortened). To put this value of 15 frames or more per second into
perspective, the following examples are provided:
Example 1
[0074] With a speed of 15 frames per second (fps), and a person
moving approximately 10 cm per frame, the system of the present
invention captures targets without losing processed information
before the subject moves too far. If the speed decreases by 5 fps,
the system would lose a tracked target because that target will
have shifted 30 cm and may already cross into a neighboring
trajectory channel of waves. Thus, a higher fps allows for such
real-time processing while also providing the capability of
processing several targets at once. In general, the more frames per
second, the greater the performance and probability of detection,
since all frames are used in the analysis independently and in
combination contribute to any final alarm decision.
[0075] Current prior art in the field of invention is limited by
data processing time (typical time is a few seconds). In the case
of screening one target at a time (e.g., through a doorway/portal),
or in the case of screening moving subjects, or in the case of
screening non-moving targets while processing the data, the prior
art comprises technology having a maximum of 15 fps. The present
invention, however, is capable of operation at greater than 15 fps
and applies to both moving and non-moving targets, at a rate of 15
fps or more, wherein the collection/capturing of data may occur in
parallel with the processing of the same data.
[0076] Standoff Detection at Longer Distances.
[0077] The present invention is capable of inspecting an area as
long and wide as 3 meters (or less), and/or an area as long as 6
meters (or less). The size of a given embodiment and inspection
area may depend on specific factors such as, but not limited to,
visibility zone of video, visibility zone of microwave imaging, and
system resolution requirements.
[0078] Multi-Threat Detection of Explosives and Metallic Weapons
Simultaneously.
[0079] Multi-threat detection of both explosives and metallic
weapons, at the same time, and in real time, is achieved by the
following aspects of the present invention: (1) each transmitter
uses the same source of microwave irradiation; (2) various
scattered polarization is detected by the same receiving antenna
but turned 90 degrees (i.e., the same design receiving antenna
turned 90 degrees about its axis of symmetry, such that the antenna
receives cross-polarizations of transmitted signals); (3) a
receiving antenna placed at 0 degrees, in relation to (2), for
collecting initial polarization of transmitted and scattered
signals (i.e., for receiving co-polarizations); (4) A calculated
ratio of co-polarizations and cross-polarizations (collected
preferably as described herein, i.e., antennas placed at "0" and
"90" degrees) allows for detection of separate explosives threats
and metallic object threats (see, e.g., FIGS. 14A-14B); and (5) a
unique algorithm for separately reconstructing two 3D microwave
images, one with regard to co-polarizations and the other with
regard to cross-polarizations, for the detection and the separation
of multiple threats potentially located on multiple targets
simultaneously and in real time (i.e., signal measurement in
parallel with processing of signals measured), which occurs via a
final determination made by the system after combining information
from each 3D microwave image, also in combination with any video
Images Obtained.
[0080] High probability of detection coupled with a low false alarm
rate.
[0081] The ability of the present invention to process data in real
time, and to collect and analyze all frames during a subject's
movement within the zone of inspection, allow for a high
probability of detection. The ability of the present system to
combine information from two receiving blocks (e.g., explosives and
metal detection) increases the performance of the processing and
analysis of signals but also lowers the chances of a false alarm
which would disturb the movement of all subjects within the
inspection area.
[0082] The present invention generally describes apparatuses,
including portals and detectors for detecting hazardous and/or
radioactive materials, and methods for signal processing, decision
making and/or for using the apparatuses. It should be understood
that these apparatuses and methods are adapted to be used on a
variety of subjects and in a variety of settings, including people,
packages, conveyances, buildings, outdoor settings, and/or indoor
settings. Also, within the scope of the invention is firmware,
hardware, software and computer readable-media including software
which is used for carrying out and/or guiding the methodologies
described herein, particularly with respect to radioactive (and
nuclear) threat detection. Hardware optionally includes a computer,
the computer optionally comprising a processor, memory, storage
space and software loaded thereon. The present invention has been
described using detailed descriptions of embodiments thereof that
are provided by way of example and are not intended to limit the
scope of the invention. The described embodiments comprise
different features, not all of which are required in all
embodiments of the invention. Some embodiments of the present
invention utilize only some of the features or possible
combinations of the features. Variations of embodiments of the
present invention that are described and embodiments of the present
invention comprising different combinations of features noted in
the described embodiments will occur to persons of the art. When
used in the following claims, the terms "comprises", "includes",
"have" and their conjugates mean "including but not limited to".
The scope of the invention is limited only by the following
claims.
[0083] The description of a preferred embodiment of the invention
has been presented for purposes of illustration and description. It
is not intended to be exhaustive or to limit the invention to the
precise forms disclosed. Obviously, many modifications and
variations will be apparent to practitioners skilled in this art.
It is intended that the scope of the invention be defined by the
following claims and their equivalents.
[0084] Moreover, the words "example" or "exemplary" are used herein
to mean serving as an example, instance, or illustration. Any
aspect or design described herein as "exemplary" is not necessarily
to be construed as preferred or advantageous over other aspects or
designs. Rather, use of the words "example" or "exemplary" is
intended to present concepts in a concrete fashion. As used in this
application, the term "or" is intended to mean an inclusive "or"
rather than an exclusive "or". That is, unless specified otherwise,
or clear from context, "X employs A or B" is intended to mean any
of the natural inclusive permutations. That is, if X employs A; X
employs B; or X employs both A and B, then "X employs A or B" is
satisfied under any of the foregoing instances. In addition, the
articles "a" and "an" as used in this application and the appended
claims should generally be construed to mean "one or more" unless
specified otherwise or clear from context to be directed to a
singular form.
* * * * *