Note: Descriptions are shown in the official language in which they were submitted.
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Field of the Invention
The invention relates to a security seal and more
particularly to a tamper-resistant, field-identifiable, fiber
optic, security seal which can be continuously mor.itored for
integrity and indentity.
Background of the Invention
Typically, prior art security seals have employed
metal tapes or wires whose ends are joined by one-time-use
clasps, interlocking metal or plastic cups, or moldable
material carrying an inscribed serial number or other type of
identifiable mark. Some types of seals have, in addition,
randomly inscribed marks or randomly distributed particles
which are photographed prior to use and are re-photographed
after the seal has been removed and disassembled. Still
other seals.are identiied with the aid of ultrasonic scanners.
Although these types of seals are generally effective, they
cannot withstand sustained attach, may be counterfeited, a~e
usually not reusable, and cannot be continuously monitored.
Fiber optic seals with juxtaposed and twisted
ends are described in U.S. patent 3,854,792 (Koelle). In dev~ces
described ln that patent, half of~the joine~ end is illuminated,
ing a unique pat~rn-o~ light on the other half.
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It is an object of the present in~ention to pro-
vide a tamper-resistant, iber optic security seal.
Accordinglyt the present invention provides fiber
optic seal apparatus comprising a block, first and second
pathways crossed within the block, the pathways having
openings in spaced relationship on facial areas of the
block, bundle holding means connected to the block for
holding an optic fiber bundle end inserted in each pathway
with portions of the fibers near one end of the bundle
threaded between portions of the fibers near the opposite
end of the bundle in r~ndom arrangement within the block
with a medial portion of the bundle passing through an
object to be sealed.
In the described embodiment to make a seal, an
appropriate length of fiber optic bundle material is cut;
~ two tapered collars are placed on the fiber bundle near
¦ ~ach end, and approximately 1.25" of the protective plastic
jacket is remo~ed from each end oI the bundle. One of the
stripped ends of the fiber bundle is then fully inserted
into one-of the two cylindrical holes in the bottom edge
of the fiber locking assembly and is secured by seating the
tapered collar. The free end is then similarly inserted
in the remaining cylindrical hole and secured. The internal
componer.ts of the fiber locking assembly block are designed
to flatten the ~tripped fiber bundle ends into a fan shaped
array of fihers so that the fibers from one end of the
bundle may easily intersect and pass randomly in between the
fanned fibers of the other end. The ends of the fibers
above the intersection will now appear in ~he cylindrical
holes at the top or exit edge of the assembly block. The
fibers in the two fars are then recombined into two ind~-idual
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bundles by modified tapered collars analogous to those used
to secure the jacketed fiber bundle at the base of the fiber
locking assembly. These tapered collars hold the loose
fibers firmly in place at the top edge of the.seal.
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The identity of the seal is established in the field
by using a small, hand-held microscope and illuminator. The
completely assembled seal is placed in the indexing stage of
the field microscope. One end of the fiber optic bundle is
illuminated by light from a pen-sized flashlight through a
60 degree prism or mirror. All of the fiber ends are illuminated
by this reflected light with the exception of those fibers
lying directly under a reticle containing at least one opaque
line whose width is approximately equai or slightly larger
than the diameter of the optic fibers used in the fiber bundle.
This reticle may be rotated through an angle of 180 degrees with
its center of rotation coinciding with the geometric center of
the bundle. In this manner the light entering every fiber in
the bundle may be controlled. A provision is made for measuring
the angle of rotation of this reticle. The light transmitted
through the fibers and emerging at the opposite end of the bundle
is magnified and optically examined with the field microscope.
The angular position and radial distance from the center of the
field of view of the microscope (i.e. the polar coordinates r, ~)
of a selected, small set of individual fibers may be measured
using the eyepiece reticle and recorded along with the seal's
serial number. This position data may be supplemented by
additional observations on the size, color, imperfections, and
optical transmission properties of the individual fibers. Such
data obtained on a small, well dispersed number of fibers
~approximately 5) should be sufficient to uni~uely identify a seal
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and should provide reasonable assurance that substitution or
counterfeiting of a seal could not go undetected. Alternatively,
a photomicrograph may be taken of the random pattern formed by
the fiber ends in the field of view of the microscope using a
Polaroid or film camera. The photographic procedure is recommended
where the highest level of confidence is required and when it
must be determined that a seal left unattended and unexamined
for significant intervals of time has not been compromised.
The security of this type of fiber optic seal depends
upon: (1) the unique fingerprint which is generated by the
totally random pattern at the ends of the fiber optic bundle,
(2) the unique scrambled or decoded image of the line reticle
introduced at the illuminated end of the fiber bundle, (3) the
ability to verify the optical continuity of every fiber in the
bundle, (4) the necessity to completely destroy the fingerprint
during disassembly, (5) the formidable problem which would be
encountered in any effort to duplicate this unique fingerprint,
and (6) the equally formidable problem of reestablishing the
light transmitting capability of the individual fibers interrupted
in the process of cutting the fiber bundle.
If there is a requirement to continuously monitor
a fiber optic seal, the fiber locking assem~ly block may be
inserted into a solid state monitoring device. The monitor
contains a pulsed LED light source which is used to illuminate
one end of the fiber bundle, a photo-transistor circuit which
detects the light transmitted through the fiber optic loop,and
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a microprocessor with the necessary associated components to
generate and display, or transmit on demand a time ordered
random number. Interruption of the light transmitted through
the fiber optic bundle, harassment of the electronic monitor,
or electronic failure will clear the random number generator
with only the last undisturbed number remaining in the memory
of the unit. These electronic components are housed in a small,
secure, tamper-indicating container, such as a stressed glass
cut. The order of the random number generated within the
monitor is known only to the organization which has
installed the seal. The random number sequence generated by
each seal is, of course, also unique to that seal alone. The
random number generated by the monitor may be displayed on
demand to either the inspector, the facility operator where
the seal is installed, or the number may be transmitted to
the organizational headquarters.
Another object of the em~od~men~ is-to pro~id~-~
_ .
security seal whose unique identity and optical integrity can
be verified in the field without disassembly or the removal of
the seal.
Another object of the embodiment is to provide-a
tamper-resistant seal which can be applied in a wide variety
of hostile environments and which is capable of withstanding
sustained attempts to defeat the seal.
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Anoth~r object of the embodiment is to provide a ~eal
which can be identified in the field by using either visually
obtained microscopic data on the position and appearance of
individual fibers or by using photomicrographic methods to
record the fingerprint and decoded image of the line reticle
formed by the random distribution of the optical fibers at the
end of the bundle.
Still another objective of the embodiment is to
provide a tamper-resistant seal which can be continuously monitored
for its optical integrity and identity over sustained periods
during which the seal will be unattended.
One advantage of the present embodiment ~s that the
fiber optic seal is tamper resistant.
Another advantage of the embodiment is that-the
identity and optical integrity of the seal can be established
in the field without removal or disassembly of ~he seal.
Another advantage of the embodiment is that the seal
can be continuously monitored in the field for its optical
integrity and identity, and if desired, an encoded status
report on the seal transmitted to headquarters.
Another advantage of this seal is that it is easily
and quickly installed during field operations.
Yet another advantage of the seal is that it is
reusable and that it can ~e easily applied in a wide variety
of situations.
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One object of the embodiment is the provision of a
fiber optic seal having a block with crossed pathways having
openings in spaced relationship on facial areas of the block
and an optic fiber bundle in a pathway within the block.
Another o~ect of the e~bodiment is the provision of a
fiber optic seal with a holder for mounting a portion of an
optic fiber bundle in an opening at the end of a pathway in a
block.
The embodiment nas as a further objèct the provision of
a fiber optic seal with a chuck having an inner bore receiving
a fiber optic bundle, having an outer portion which engages
a passageway and having a tapered outer portion with a slit
extending from the tapered outer portion to the bore, whereby
the tapered outer portion is compressed upon a bundle, and a
collet having an outer portion fitting within the passageway
wall having a ~apered inner opening for c~operating with the
tapered outer portion of the chuck to clamp a fiber optic bundle.
Another object of the embodiment is the provision of
a fiber optic seal having a spreader mounted near an intersection
of passageways in a block for spreading fibers in a fiber optic
bundl~. .
A further object of the embodiment is the pro~ision
of optic fiber spreaders having outer-portions for fitting in
walls of passageways, having distal ends facing outward in the
passageways and having proximal ends for positioning near an
intersection o~ the passageways, the spreaders having bores
extending inward from distal ends and having channels extending
inward from the bores, the channels being generally rectangular
in cross section and having a transverse dimension less than a
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similar transverse diametrical dimension of the bore, whereby
fibers are restricted in that direction and are spread and fanned
outward in the channels.
A further object of the embodiment is the provision
of optic fiber spreaders as described wherein proximal ends of
the inserts are configured for interengaging and abutting
proximal ends of other inserts.
Another object of the embodiment is the provision
of a fiber optic seal with a fiber optic bundle having a first
end positioned in one pathway in a block, having a medial portion
extending from the block and having a second end remote from
the block.
Another object of the embodiment is the provision of
a fiber optic seal wherein a portion of a first end of a fiber
optic bundle positioned within an intersection of the pathways
in a block has fibers arranged to r~ndomly receive crossed
fibers in interstices between fibers.
t Another object of the em~odiment is the provision of
a fiber optic seal wherein a terminus of a bundle is tightly
held in a facial opening at the end of a first passageway in a
block, and wherein a portion of a fiber optic bundle which
emerges from an opening at the opposite end of the first
passageway is tightly held in that opening.
The embodLment has as a further object the provision
of a fib~r optic seal as described wherein a free end of the
fiber optic bundle has an outer covering removed from a length
of the bundle from a remote terminus of the bundle at least as
far along the bundle as a distance from an intersection to an
opening of a second passageway in the block.
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Another object of the embodiment is the provision
of a fiber o~tic seal having means for selectively controllins
the light source for selected illumina~ion of optic fiber
termini at one end of a bundle.
- A further object of the embodiment is the provision
of a fiber optic seal with a reticle between a light source
and fiber termini and means for moving the reticle.
The embodiment has as a further object the provision
of a fiber optic seal with a reticle having an opaque line
diametrically positioned across an optical axis connecting a
light source and a medial portion of fiber termini, the line
being slightly wider than a fiber diameter, and a rotatable
wheel on which the reticle is positioned.
A further object of the embodiment is~~he provision
of a fiber optic seal having a fiber optic bundle with a
plurality of coextensive and coterminal optical fibers held
together with portions of the fiber near one end of the bundle
threaded between portions of the fibers near the opposite end
of the bundle in random arrangement, means to separate}y hold
first and second remote termini of the bundle of fibers, means
fQr introducing light into the first termini, and means for
ob~erving light in the second termini, and means for predeter-
minately interrupting light in the first termini and means for
recording locus of fiber ends in the second termini showing
characteristics of interrupted light.
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Another object of the embodiment is~the provision
of a fiber optic seal with a fiber optic bundle ~ith a medial
portion for engaging an object to be sealed and end portions
having randomly interspersed fibers, means for holding termini
of the fibers and means for eliminating some of the termini and
means for receiving illumination of other of the termini,
reticle means for interposing between the illuminating means
and said some of the termini for selectively partially
preventing illumination, and means for moving the reticle
means for changing the masking.
.
An embodiment of the invention will now be described,
by way of example, with reference to the accompanying drawings
in which:-
Figure 1 shows a schematic ~i~w of the field identi-
fiable fiber optic seal. - -
Figure 2 is a view of an assembled seal including thefiber locking assembly block and a fiber optic bundle.
Figures 3 and 4 show the hand-held microscope, il-
luminator, seal, and fiber locking assembly block in more
detail.
Figure 5 is an exploded view, showing the internal
construction of the fiber locking assembly block.
Figures 1 through 4 show a field assembled, fiber optic
seal l,-fiber optic bundle 2 and fiber-locking block assembly 4
inserted in the indexing stage 6 of a hand-held field micro-
scope 8 and illuminator 10 and the camera 12 used to take the
identification photo micrograph.
To assemble the seal 1 the following operations are per-
formed: An appropriate length of fiber optic ~undle material
is cut to the length required to apply the seal. Two tapered
collars 14 and 16, as shown in Figure 5, are inserted over
the ends of the fiber optic bundle. Approximately 1 1/4 inch
of the plastic jac3ceting 18 surrounding the fiber optic bundle
is removed from each end of the bundle. One end 20 of the
fiber optic bundle 2 is fully inserted into one of the openings
22 in the bottom face 24 of the fiber locking assembly block 4.
Tapered collar 14 is securely seated into one passageway 26.
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The free end of the fiber optic bundle is threaded through
the object to be sealed and is then inserted into the re-
maining cylinderical passageway 28 in assembly block 4. The
tapered collar 16 is seated and secured. On completion of
these steps the fiber optic bundle 2 is now firmly held in
place by the tapered collars 14 and 16. The interior
components 30, 32, 34 and 36 of the fiber locking
assembly block (shown in Figure 5) flatten the optical fibers
permitting them to easily intersect at intersection 40 and
pass through each other and throuqh openings 42 and 46 at the
opposite faces 44 and 48 of the fiber locking block 4.
The seal is completed by inserting and firmly seating
the tapered collars 50 and 52 in the top openings 42 and 46
of the top faces 44 and 48 o~ the assembly block 4. This
operation brings the fanned fibers termini 54 and 56 into
two circular bundles and holds them securely in place.
The identity and optical integrity of the seal is
established in the field by inserting the fiber locking block
4 of the completed seal into the inde~ing stage 6 of the hand-
held microscope illuminator 8 and 10. The symmetry of the
fiber locking assembly block permits either bundle end to be
observed under the microscope 8. The orientation of the
fiber locking assembly may be determined by the presence of
the symbol such as "~" 58 in a vie~ing port 6~ on the side
of the indexing stage 6. The opposite end of the fiber optic
bundle is il~uminated through a 60 degree prism 62 by a small
pen-sized flashlight 10. A reticle 64 lies in a plane between
the light source 10 immediately above the ends of the fiber
bundle being illuminated. The reticle 64 contains at least
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one inscribed, opaque line 66 whose width is equal or slightly
greater than diameters of the fibers used in the fiber bundle
2. This reticle may be rotated through 180 degrees and the
reticle holder 68 is appropriately indexed so that it is
possible to measure the angle of rotation of the reticle 64.
Rotation of the reticle 64 permits the controlled illuminat-
ion of every fiber in the bundle. In addition, the image of
this line reticle transmitted by the fiber optic bundle will
be scrambled or decoded at the opposite end of the bundle be-
cause of the random orientation of the fibers in the two ends
of the fiber optic bundle. Under the microscope the line
ima~e will appear as a series of randomly distributed,
darkened fibers, which will resume light transmission as the
reticle is rotated.
The magnification and the field of view of the hand-
held microscope is adjusted so that all of the fibers at the
light transmitting end of the bundle can be observed. The
eye piece 70 of the microscope 8 is equipped with an additional,
rotatable reticle 72,with which the observer may measure both
the distance of a sing~e fiber from the center of the field of
view of the microscope as well as the angle through which
the reticle must be rotated from a fixed, indexed point in
order to intersect the image of the fiber end. To identify
a seal, the observer notes the polar coordinates of a
small selected number of fibers whose illumination can be
controlled by the rotatable line reticle 64. The position of
the line reticle may be fixed at 0 or it may be set at
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some other predetermined angle by the observer. A serial
number on the block and the reticle degree are recorded in
a notebook. The observer then measures for the specifically
darkened fiber, the radial distance from the center of the
field of view and angle of the fiber from the 0 point, using
the reticle in the eye piece of the microscope. This informat-
ion is also recorded in the same field notebook. In addition
to the polar coordinates of this particular group of fibers,
the observer may in addition record information on the size,
color, imperfections in the fiber ends and the light trans-
mitting properties of the fibers. On a subsequent visit the
identity and optical integrity of the seal is re-established
by inserting the seal into the stage of the hand-held micro-
scope and reconfirming the polar coordinates data and
characteristics previously recorded at the time that the seal
was assembled.
For certain seal applications, it may be desirable to
supplement the type of information o~tained using the illuminat-
ion and eyepiece reticles by making a photo micrograph of all
of the fibers in the end of the bundle being observed. This
photo micrograph may be made by attaching camera 12 fitted
with an adapter 74 to the microscope occular. It is recommended
that if a Polaroid camera is to be used fro the initial photo
micrograph taken immediately after the assembling of the seal,
Type 105P/N film ~e used in order that a negative of the fiber
bundle image may be obtained. ~his negative is then marked
with the serial number of the seal, the angular position of
the line reticle and is filed for future reference. On
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subsequent occasions when the identity and integrity of the
seal must be checked, a Polaroid*positive print is made
and the original negative is placed over the positive print.
Even extremely small variations in fiber position, shape
imperfections and light transmitting properties can be
detected in this manner. The proba~ility that this degree
of replication can be counterfeited is highly unlikely and
therefore this seal represents a maximum level of protection.
~ he present fiber optic seal design can, if the situation
requ~res, be supplemented by an electronic monitor which con-
tinuously checks the optical integrity and the identity of
the seai during periods when the seal must be left unattended.
The condition of the seal may be reported on a fixed schedule
by the host facility where the seal has been applied and
checked by an inspector during a routine inspection. It is
possible that the output of the monitor can be transmitted
directly to the headquarters of the inspecting agency if very
prompt notification of a seal failure or of an attempt to
remove the seal is required.
As shown in Figure S, clamps 14, 16, 50 and 52 have
two parts 76 and 90. Bore 78 receives fiber optic bundle 2
and outer wall 8~ engages an inner wall of the passageway.
Tapered portion 82 has a slit 84 which extends through 6 bore
78. Collet 90 has an outer wall which tightly ~interference
fit) engages the inner cylindrical wall of passageway 26.
Slope g4 is a few degrees different than the slope of taper 82.
Consequentl~l when collet 90 is forced inward, taper 82
*Trademark
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compresses to decrease bore 78, gripping bundle 2. Fiber
spreading inserts 96 have faces 98, which abut chucks ~6,
and internal faces 100 which are configured to abut and
interengage similar internal faces. Tapers 102 direct
fibers in bundles 2 into spreading channels 104, which
extend across the inserts in one direction, and which are
laterally restricted in a transverse direction. The combined
inserts fan fibers at their intersection, facilitating
random interspersions of fiber ends in inter`stices between
previously inserted fibers.
Internal tapers 106 and external slopes 108 assure
correct interfitting of the inserts.
While the invention has been described with reference
to specific embodiments, modifications and variations may be
constructed and used without departing from the scope of the
invention, which is defined in the following claims.
