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Claims  |
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What is claimed is:
1. A fiber image guide based bit-parallel interconnect comprising:
a fiber image guide comprising material selected from the group consisting
of a flexible fiber bundle guide, a rigid fiber bundle guide which can be
bent only while heated to a predetermined temperature, a rigid and
unbendable graded-index glass guide and a flexible graded-index plastic or
polymer guide;
a laser array for providing a bit-parallel optical format signal;
a first imaging means for imaging the bit-parallel optical format signal
onto a first end of said fiber image guide;
a second imaging means for imaging the bit-parallel optical format signal
from second end of said fiber image guide as an output data pattern onto
an output plane, and
detector means disposed at said output plane for converting said output
data pattern into electronic data.
2. A fiber image guide based bit-parallel interconnect as set forth in
claim 1, where said second imaging means magnifies said bit-parallel
optical format signal from said fiber image guide.
3. A fiber image guide based bit-parallel interconnect as set forth in
claim 1, where said laser array comprises individual lasers.
4. A fiber image guide based bit-parallel interconnect as set forth in
claim 1, where said laser array comprises a geometrically configured
arrangement of lasers.
5. A fiber image guide based bit-parallel interconnect as set forth in
claim 4, where said geometric arrangement is a two-dimensional cartesian
array.
6. A fiber image guide based bit-parallel interconnect as set forth in
claim 1, where said first imaging means demagnifies said bit-parallel
optical format signal.
7. A fiber image guide based bit-parallel interconnect as set forth in
claim 6, where said second imaging means magnifies said demagnified
bit-parallel optical format signal from said fiber image guide.
8. A fiber image guide based bit-parallel interconnect as set forth in
claim 1, where said first imaging means comprises a fiber taper.
9. A fiber image guide based bit-parallel interconnect as set forth in
claim 1, where said first imaging means and said second in, aging means
comprise fiber tapers.
10. A fiber image guide based bit-parallel interconnect comprising:
a fiber image guide;
a laser array for providing a bit-parallel optical format signal;
a first imaging means for imaging the bit-parallel optical format signal
onto a first end of said fiber image guide;
a second imaging means for imaging the bit-parallel optical format signal
from a second end of said fiber image guide as an output data pattern onto
an output plane, where said first imaging means and said second imaging
means comprise fiber tapers of different cross-section ratios, and
detector means disposed at said output plane for converting said output
data pattern into electronic data.
11. A fiber image guide based bit-parallel interconnect as set forth in
claim 1, where said laser array provides a bit-parallel optical format
signal of electrical bit-parallel data.
12. A fiber image guide based two way bit-parallel interconnect comprising:
a fiber image guide;
a first laser array for providing a first bit-parallel optical format
signal of electrical bit-parallel data;
a first imaging system disposed for coupling said first bit-parallel
optical format signal for transmission along said fiber image guide;
a second imaging system disposed for receiving said transmitted said first
optical format signal from said fiber image guide, where said first
imaging system and said second imaging system comprise a beam-splitter;
a first detector means for receiving a first imaged optical format signal
from said second imaging system and converting same to an electrical
bit-parallel data signal;
a second laser array for providing a second bit-parallel optical format
signal of electrical bit-parallel data to said second imaging system for
coupling to said fiber image guide, and said first imaging system disposed
for receiving said transmitted said second optical format signal; and
a second detector means coupled to said first imaging system for receiving
a second imaged optical format signal from said first imaging system and
converting same to an electrical bit-parallel data signal.
13. A fiber image guide based two-way bit-parallel interconnect as set
forth in claim 12, where said first laser array and said second detector
means are in substantially the same plane.
14. A fiber image guide based two-way bit-parallel interconnect as set
forth in claim 13, where said second laser array and said first detector
means are in substantially the same plane.
15. A fiber image guide based two-way bit-parallel interconnect as set
forth in claim 12, where said first laser array comprises a plurality of
fiber image guides.
16. A fiber image guide based two-way bit-parallel interconnect as set
forth in claim 12, where said first detector means comprises a plurality
of fiber image guides.
17. A fiber image guide based two-way bit-parallel interconnect as set
forth in claim 12, where said first laser array and said first detector
means comprise a plurality of fiber image guides.
18. A fiber image guide based two-way bit-parallel interconnect as set
forth in claim 12, where said first imaging system comprises a fiber
taper.
19. A fiber image guide based two-way bit-parallel interconnect as set
forth in claim 12, where said first imaging system and said second imaging
system comprise fiber tapers.
20. A fiber image guide based two way bit-parallel interconnect comprising:
a fiber image guide;
a first laser array for providing a first bit-parallel optical format
signal of electrical bit-parallel data;
a first imaging system disposed for coupling said first bit-parallel
optical format signal for transmission along said fiber image guide;
a second imaging system disposed for receiving said transmitted said first
optical format signal from said fiber image guide, where said first
imaging system and said second imaging means comprise filter tapers of
different cross section ratios;
a first detector means for receiving a first imaged optical format signal
from said second imaging system and converting same to an electrical
bit-parallel data signal;
a second laser array for providing a second bit-parallel optical format
signal of electrical bit-parallel data to said second imaging system for
coupling to said fiber image guide, and said first imaging system disposed
for receiving said transmitted said second optical format signal, and
a second detector means coupled to said first imaging system for receiving
a second imaged optical format signal from said first imaging system and
converting same to an electrical bit-parallel data signal.
21. A fiber image guide based two-way bit-parallel interconnect as set
forth in claim 12, where said first laser array comprises a plurality of
fiber image guides and said first imaging means comprises a fiber taper.
22. A fiber image guide based two-way bit-parallel interconnect as set
forth in claim 12, where said first detector means comprise plurality of
fiber image guides and said second imaging means comprises a fiber taper.
23. A fiber image guide based two-way bit-parallel interconnect as set
forth in claim 12, where said first laser array comprises a plurality of
fiber image guides, said first detector means comprises a plurality of
fiber image guides and said first imaging means and said second imaging
means comprise fiber tapers.
24. A fiber image guide based two way bit-parallel interconnect comprising:
a fiber image guide;
a first laser array for providing a first bit-parallel optical format
signal of electrical bit-parallel data;
a first imaging system disposed for coupling said first bit-parallel
optical format signal for transmission along said fiber image guide;
a second imaging system disposed for receiving said transmitted said first
optical format signal from said fiber image guide;
a first detector means for receiving a first imaged optical format signal
from said second imaging system and converting same to an electrical
bit-parallel data signal;
a second laser array for providing a second bit-parallel optical format
signal of electrical bit-parallel data to said second imaging system for
coupling to said fiber image guide, and said first imaging system disposed
for receiving said transmitted said second optical format signal, and
a second detector means coupled to said first imaging system for receiving
a second imaged optical format signal from said first imaging system and
converting same to an electrical bit-parallel data signal,
where said fiber image guides spatially divides said first optical format
signal and said second optical format signal traveling along said fiber
image guide.
25. A fiber image guide two-way bit-parallel interconnect as set forth in
claim 24, where said first optical format signal and said second optical,
format signal are interlaced.
26. A fiber image guide two-way bit-parallel interconnect as set forth in
claim 24, where said first optical format signal and said second optical
format signal travel along separate regions of said fiber image guide.
27. A fiber image guide based two way bit-parallel interconnect comprising:
a fiber image guide;
a first laser array for providing a first bit-parallel optical format
signal of electrical bit-parallel data;
a first imaging system disposed for coupling said first bit-parallel
optical format signal for transmission along said fiber image guide;
a second imaging system disposed for receiving said transmitted optical
format signal from said fiber image guide;
a first detector means for receiving a first imaged optical format signal
from said second imaging system and converting same to an electrical
bit-parallel data signal;
a second laser array for providing a second bit-parallel optical format
signal of electrical bit-parallel data to said second imaging system for
coupling to said fiber image guide, and said first imaging system disposed
for receiving said transmitted said second optical format signal; and
a second detector means coupled to said first imaging system for receiving
a second imaged optical format signal from said first imaging system and
converting same to an electrical bit-parallel data signal,
where said fiber imaging system comprises a low-pass interference filter
and said second imaging system comprises a high-pass interference system.
28. A fiber image guide two-way bit-parallel interconnect as set forth in
claim 27, where said first optical format signal and said second optical
format signal are at different wavelengths. |
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Claims |
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Description |
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FIELD OF THE INVENTION
The present invention relates to a fiber image guide for establishing
bit-parallel computer data communications. Specifically, a fiber image
guide is located between an input laser transmitter array where each laser
is driven by an output from a first computer chip and an output receiver
array where each receiver output signal is coupled to an input of a second
computer chip.
BACKGROUND OF THE INVENTION
Fiber image guides, both coherent fiber bundles or single gradient-index
fibers, are used for transmitting image signals from one end of the guide
to the other end of the guide. A typical fiber bundle contains thousands
of individual fiber pixels disposed in an ordered and coherent manner at
their end termination. Such a fiber image guide has been successfully used
in various medical endoscopic and industrial inspection applications. High
resolution analog images have been achieved for certain image guides
having a length of several meters. Relatively low loss (e.g. 2 dB over a
distance of 10 meters) transmission can be achieved at certain
transmission wavelengths by the selection of the materials used to
fabricate the fiber image guide.
Modern information oriented sciences and technology are mainly driven by
rapid advances in computer technology. One visible trend in computer
hardware technology is that the central processing units or CPUs will
process data in larger and larger parallel formats, from 8-bits in early
1980's, to 16-bits or 32-bits in mid 1980's, and to 64-bits or more in
1990's. In order to avoid unnecessary delays, technology for parallel
communication channels between such CPUs and memory or input/output (I/O)
devices must also be rapidly developed. Unfortunately, due to inherent
bandwidth limits and electronic interference, large degree parallel
electronic communication channels are very difficult to establish,
especially where the communication distance is long, for instance longer
than a few centimeters. A previously proposed solution was to use
fiber-telecommunication teleology where a large amount of parallel
information is transmitted in a time-multiplexed serial format. A
limitation of this kind of arrangement is that as the bit-rate in each
parallel channel increases, electronic hardware for multiplexing and
demultiplexing will experience an increasing burden. For example, for a
moderately high bit-rate of 500 Mhz/bit-channel, a 32-bit communication
will have to use a pair of multiplexer/demultiplexer of 16 GHz, making the
hardware very difficult to develop.
SUMMARY OF THE INVENTION
The present invention overcomes these limitations and provides a design for
a fiber image guide based bit-parallel computer data communications.
Fiber image guides are presently available for use in computer oriented
parallel digital inter-connection application. Since the interconnection
distances typically are in a range from several centimeters to several
meters, absorption losses and long-distance cross-talk between imaging
pixels does not present a significant problem.
In accordance with the teachings of the present invention, a fiber image
guide is employed to transfer bit-parallel data from a first circuit to a
second circuit. The arrangement can be either one-way communication or
two-way communication in the same fiber image guide.
Lens assemblies magnify and demagnify the optical data pattern into and out
of the guide. Beam splitters, mirrors, fiber tapers are incorporated into
the lens assembly for directing the two-way data transmission from and to
respective transmitter laser arrays and detector receiver arrays.
Band-pass interference filters may be used when transmitting two-way data
along the fiber image guide at different wavelengths.
A principal object of the present invention is therefore, the provision of
a system for communicating bit-parallel data using a fiber image guide.
The present invention will be more clearly understood when the following
description is read in conjunction with the accompanying drawing.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an illustration of a conventional fiber image guide;
FIG. 2 is a schematic illustration, partially in cross-section, of a
one-way bit-parallel optical data transmission path using a fiber image
guide;
FIG. 3 is a schematic illustration, partially in cross-section, of a
two-way bit-parallel optical data transmission path using a fiber image
guide;
FIG. 4 is a schematic illustration, partially in cross-section, of an
alternative embodiment of a two-way bit-parallel optical data transmission
path using a fiber image guide;
FIG. 5 is a cross-sectional illustration of the interconnection of an
alternative embodiment for a bit-parallel optical data transmission path
using a fiber image guide;
FIG. 6 is a modification of the embodiment shown in FIG. 2 which
modification incorporates fiber tapers;
FIG. 7 is a modification of the embodiment shown in FIG. 3 which
modification incorporates fiber tapers;
FIG. 8 is a modification of the embodiment shown in FIG. 5 which
modification incorporates fiber tapers;
FIGS. 9A and 9B are schematic representations of preferred space division
embodiments for separating input and output optical data patterns; and
FIG. 10 is a schematic representation of a two-way bit-parallel optical
data transmission arrangement using a low-pass filter and a high-pass
filter.
DETAILED DESCRIPTION
Referring now to the figures and to FIG. 1 in particular there is shown a
conventional bundle fiber image guide 10 having thousands of individual
fiber pixels disposed in an ordered and coherent manner at their end
terminations 12, 14. This type of fiber image guide has proven success for
analog imaging applications in medical endoscopy and in industrial
inspection applications.
FIG. 2 shows a one-way bit-parallel optical data transmission system for
sending digital parallel messages between two digital chips or circuit
boards. The system includes an input electronic circuit board 16 from
which bit-parallel digital electronic data are to be transmitted. A two
dimensional laser array chip 18 which converts the bit-parallel digital
electronic data into a corresponding bit-parallel optical format signal.
An input imaging lens or lens compound 20 acts as an objective lens for
imaging the bit-parallel optical format signal onto the first end surface
22 of a fiber image guide 24. The fiber image guide transmits the optical
signal from the lens 20 to a remotely located objective imaging lens or
lens compound 26 which receives the signal from the second end surface 28
of the fiber image guide 24. The objective imaging lens 26 magnifies and
images the transmitted digital optical data pattern onto an output plane
where an output two dimensional optical detector array chip 30 converts
the digital output data pattern into a digital electronic data format. The
signal from the detector array chip 30 is received by an electronic
receiver circuit board 32 to which the original digital bit-parallel data
from transmitter circuit board 16 was sent.
The above system also includes optic-mechanical mountings and connectors 34
as shown in FIG. 2. The male connectors 34 are connected to the respective
ends of fiber image guide 24. Likewise the female connectors 38, 40, which
also support the respective array chips 18 and 30, may be either standard
or specially designed connectors for mating with connectors 34. In
general, the mechanical precision of the mounting of the fiber image guide
24 to the male connector 34 should be comparable to that used for mounting
multi-mode fibers.
The fiber image guide, preferably, is selected to be one of the four
following types: a flexible fiber bundle guide, a rigid fiber bundle guide
which can be bent only while heated to a predetermined temperature, a
rigid and unbendable graded-index glass guide, or a flexible graded-index
plastic or polymer guide.
The input image lens 20, preferably, may be a conventional spherical lens
or alternatively, the lens may be a graded-index planar surface lens, such
as a SELFOC rod lens.
The laser array 18 may comprise individual lasers arranged in either a
linear array or in a two dimensional cartesian array or other geometric
configuration.
The emitted spatial optical pattern from guide 24 is demagnified to form a
smaller image at the second end surface 28 of the fiber image guide 24 if
the area of the pattern is larger than or equal to the cross-sectional
area of the fiber image guide. The smaller the area of demagnified
pattern, the easier the alignment becomes at the connector 34. A
sufficient spacing, however, should be maintained between the optical
positions of two adjacent data points (i.e., two adjacent lasers) within
the fiber image guide in order to prevent fiber cross-talk. At the output
end of the fiber guide, a magnified image of the transmitted data pattern
will be formed at the optical detector array chip 30. The magnification
ratio does not have to exactly compensate for the demagnification ratio at
the input end of the fiber image guide. In practice, in order to minimize
the amplification of noise, the spacing between adjacent high speed
detectors in the detector array is maintained larger than the spacing
between adjacent lasers transmitting data at the same high rate. Thus, the
magnified optical image of the transmitted data pattern is larger at the
detector array 30 than that at the laser array chip 20. Therefore, a
larger longitudinal dimension of the output female connector 40 than that
of the input female connector 38 is required, as shown in FIG. 2 (not
shown to scale). The detectors in array chip 30 may be linear, two
dimensional cartesian or other geometrical arrangement corresponding to
that of the laser array chip 18.
The one-way transmission system shown in FIG. 2 may be modified to create a
two-way optical bit-parallel data interconnection system as shown in FIG.
3. The two counter propagating optical beams carrying bit-parallel data
patterns are separated by an optical beam splitter 46, 58 at each end of
the system.
A first unit 42 includes a laser array chip 44 which transmits an optical
bit-parallel data pattern to a beam-splitter 46 where the data pattern is
reflected through lens 48 into end 50 of fiber image guide 52. At a second
unit 54, the received bit-parallel data pattern passes from end 55 of
guide 52 through lens 56, beam splitter 58 and lens 60 onto detector array
chip 62. In order to transmit a bit-parallel data pattern from unit 54 to
unit 42, a laser array chip 64 transmits an optical bit-parallel data
pattern to beam-splitter 58 where the pattern is reflected through lens 56
and into end 55 of fiber image guide 52. At end 50 of guide 52 the optical
data pattern passes through lens 48, beam-splitter 46 and lens 66 onto
detector array chip 68. The laser arrays 44, 64 and detector arrays 62, 68
are coupled to respective input electrical circuit boards 70, 72 and
receiver electrical circuit boards 74, 76 by conventional means.
In order to satisfy the conditions of using a smaller demagnification ratio
and a larger magnification ratio for the input and output patterns,
respectively, the beam-splitter is disposed between two lenses. The
optical sub-system, i.e., lens-beam splitter-lens, is located in separate
housings 78, 80 prior to being disposed in respective connector housings
82, 84. Moreover, the detector array chips 62, 68 are held in their
respective proper positions by virtue of mounting fixtures 63 and 69,
respectively. Using the system shown in FIG. 3, input data are reflected
by the beam-splitter and imaged with a demagnification ratio into the end
of the fiber image guide. At the opposite end the guide, the data passes
through two lenses before being imaged with a large magnification ratio on
the receiver detector array. The use of a beam-splitter inevitably results
in an unwanted image of the received pattern being provided to the laser
chip array. Arrangements for minimizing the cross-talk effects are
described below. A salient feature of the embodiment in FIG. 3 is the
modularity of the design, so that exchange and maintenance of the
apparatus are simple tasks.
The arrangement shown in FIG. 3 requires that the receiver array chip and
the laser array chip be located in planes perpendicular to each other.
FIG. 4 shows a modification of the above arrangement where by using an
additional beam reflecting mirror 86, 88, the output magnified pattern
image can be formed at a detector array 90, 92 located in the same plane
as the respective laser array chip 44, 64. It will be apparent to those
skilled in the art that in a two way optical bit-parallel data
transmission system, either a unit having the laser array chip and the
detector array in the same plane or in perpendicular planes may be used at
either opposite ends of the fiber image guide.
The above described systems are based upon the use of laser array chips and
detector array chips. In certain applications, where arrays are neither
available nor suitable or where individual optical transmitters and
receivers are more available or suitable, a modified system, such as that
shown in FIG. 5 may be used.
Instead of forming an image of an optical pattern from a transmitter array
chip, individual fiber image guides 100 each connected at one end to a
respective data source (not shown) while at the other end, the fiber image
guides are formed into a bundle 102 the output from which is imaged onto
the end surface 104 of the fiber image guide 106. Conversely, for the
received image pattern, the fiber image guides forming bundle 108 can be
individually connected via individual fiber image guides 110 to receivers
(not shown). The guides 100 carrying the image pattern to be transmitted
are smaller diameter than the guides 110 carrying the received image
pattern.
The bundles 102, 108 are connected to respective male connector 112, 114
which, in turn are inserted into respective adapters 116, 118 containing
respective imaging lens 120, 122. Each end of the fiber image guide 106 is
coupled to respective male connector 124, 126 which are inserted into the
adapters 116, 118 for coupling the data at the respective bundle 102, 108
to the image guide 106 and vice versa.
FIG. 6 shows a modification to the embodiment in FIG. 2 where either one or
both of the lenses 20, 26 between the fiber image guide and the laser
array and the detector array respectively is replaced by a coherent fiber
tapers 128, 130 whose function is to demagnify and magnifying an image
pattern respectively. A fiber taper is a rigid fiber bundle of taper
fibers of short length. Fiber tapers are described in the publication by
W. P. Siegmund entitled "Fiber Optic Tapers in Electronic Imaging," a
Technical Reference of Schott Fiber Optics Inc., 1993.
The ratio of cross-section areas at the two opposite ends of the fiber
tapers typically varies from 2 to 6. Once the fiber taper is fabricated,
the image magnification and demagnification ratios are fixed, depending
upon the direction of the image pattern through the taper.
In the embodiment shown in FIG. 6, fiber tapers are used in a one-way
bit-parallel computer data transmission system. The fiber tapers are used
to couple the bit-parallel image manifest at the laser array chip into the
fiber image guide and to couple the image pattern from the fiber image
guide to the optical detector array. An inherent advantage of such an
arrangement is that the physical contact between the components results in
stable and reliable interconnections which are important for practical
systems.
FIG. 7 shows a two-way bit parallel optical data transmission system
similar to that shown in FIG. 3, however, the lenses used to magnify the
bit-parallel data pattern provided to the receiver detector array are
replaced by fiber tapers 127, 129.
Similarly, the arrangement shown in FIG. 5 may be modified by replacing the
lenses 104, 122 used to couple the magnified bit-parallel data pattern to
the detector array chip with fiber tapers 131, 133 as shown in FIG. 8.
In each of the two-way communication embodiments described and illustrated,
it is necessary to incorporate a space-division arrangement to separate
the spatial channels of the two opposite direction data transmissions in
order to avoid feedback of some optical signals to the optical transmitter
laser array which could damage the lasers. FIGS. 9A and 9B illustrate two
preferred space division embodiments. In FIG. 9A two 4.times.4 light pixel
patterns are shown as shaded circles 140 and unshaded circles 142. The
solid border 144 represents the effective cross-section area of a fiber
image guide, one using the shaded locations and the other using the
unshaded locations. Two light signal patterns are transmitted in opposite
directions sharing the same fiber image guide. Since the two patterns are
spatially interlaced, in principle, the transmitted optical signal
patterns will be directly imaged from the respective individual lasers in
the input laser array. FIG. 9B shows an alternate arrangement where the
two counter propagating beams use a global space-division arrangement of
the type shown. The arrangement spatially separates the cross-section area
146 of a fiber image guide into two separate regions 148, 150, each of
which handle only unidirectional transmissions. The signal transmitted
will, in principle, fall onto the output detector array area which is
spatially separated from the transmitter laser array area. Either
embodiment can be used with any of the two-way bit-parallel optical
pattern transmission arrangements described. The regions 148, 150 in FIG.
9B may assume any geometric pattern and incorporate any two regions of the
image guide, not only the vertically displaced two rectangular regions
shown in the illustration.
FIG. 10 shows schematically another alternative embodiment of a two-way
bit-parallel optical data transmission arrangement which relies upon an
optical wavelength low-pass filter and an optical wavelength high-pass
filter. When a broadband optical signal illuminates a low-pass filter,
signals with optical wavelengths below a predetermined critical wavelength
will be transmitted while signals with an optical wavelength above the
predetermined critical wavelength will be reflected. Alternatively, for a
high-pass filter, signals with wavelengths above a predetermined critical
wavelength will be transmitted while signals with wavelengths below the
predetermined critical wavelength will be reflected. Such filters are
presently available in the form of thick Fourier hologram filters. In
either case the Bragg deflection angle of the filter can be made to
reflect the signal with shorter or longer wavelengths while passing the
other wavelengths.
FIG. 10 shows an embodiment using a low-pass interference filter 152, a
filter image guide 154 and a high pass filter 156. The remainder of the
embodiment is omitted for clarity. The low wavelength signals, shown by
the shaded arrows travel from a laser array through low pass interference
filter 152, though fiber image guide 154 and into high-pass interference
filter 156 where the optical signal is reflected toward a receive
detection array (not shown). The high wavelength signals shown by unshaded
arrows, traveling in the opposite direction of that of the low wavelength
signals, travel from a laser array through high-pass interference filter
156, through wave guide 154 to low-pass interference filter 152 where the
optical signal is reflected toward a receive detector array. The low-pass
filter and the high-pass filter may be used to replace the beam-splitters
shown in FIGS. 3, 4 and 7.
While there has been described and illustrated fiber image guide based
bit-parallel computer interconnect embodiments, it will be apparent to
those skilled in the art that variations and modifications are possible
without deviating from the broad principle and spirit of the present
invention which shall be limited solely by the scope of the claims
appended hereto.
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