FBI-Gauge Features
FBI-Gauge unit
Optic fiber sensing system
General performance
Maximum measurement length (*1)
5 0 [m]
10 [m]
Data sampling ratio
2.5 [H z]
10 0 [H z]
Minimum sensor spacing
0 .4 [mm]
5 [mm]
1 [mm]
5 [mm]
± 1 0 ,0 0 0 ( μ S t r ain)
± 1 0 ,0 0 0 [ μ S t r a i n ]
± 2 [μ S t r ain]
± 5 [ μS t r a i n ]
Minimum gauge length
Stress measurement:
Measurement range
Repeat accuracy
Temperature measurement (*2)
Measurement range
− 5 0 ∼ 3 0 0 ℃( P olyimide coat ed fiber )
− 2 0 0 ∼ 8 0 0 ℃( G old coat ed fiber )
Repeat accuracy
± 0. 2 [ ℃ ]
± 0 .4 [℃ ]
Main unit
Exterior dimensions and weight
Power consumption
(*1) Inquire about different fiber lengths
(*2) Displayed temperature is relative to the reference temperature.
Fuji Technical Research Inc.
Head Office:
Queen’s Tower C15F, 2-3-5 Minatomirai, Nishi-ku, Yokohama, Kanagawa
220-6215 Japan
TEL +81(0)45-650-6650 FAX +81(0)45-650-6653
Toyota Technical Center:
2-204-5, Miyukihommachi, Toyota, Aichi 473-0901 Japan
TEL +81(0)565-25-3830 FAX +81(0)565-25-3831
Nagoya Technical Center:
Ultimate Tower Sakae Ⅴ11F, 5-28-19 Sakae, Naka-ku, Nagoya, Aichi,
460-0008 Japan
TEL +81(0)52-269-1321 FAX +81(0)52-269-1322
Utsunomiya Technical Center:
Chuo Utsunomiya Building 2F, 3-1-1 Higashishukugou, Utsunomiya, Tochigi
321-0953 Japan
TEL +81(0)28-610-0870 FAX +81(0)28-610-0871
3 6 [cm]× 3 2 [cm]× 17 [cm] / 8 [kg]
5 0 [W]
Fiber B eam I nves t igat ion
Strain and temperature measurement in point, line and plane formats!!
The FBI-Gauge sensing system is designed to measure strain and temperature via optic fiber
attached to the surface of the test piece. Continuous measurement along the optic fiber
supports both point and continuous line and surface observation. FBI-Gauge does not
require large numbers of strain gauges, and is easy to set up and inexpensive.
Optic fiber
Measurement procedure
Strain and
Processing of
3-D evaluation
ODiSI hardware
3-D analysis
The ODiSI, developed by Luna Technologies in the United States, is an optical
distributed sensor interrogator for strain and temperature measurement which
uses Optical Frequency Domain Reflectometry (OFDR)* to detect microscopic-level
Rayleigh scattering within optic fiber for monitoring displacement at
millimeter-level precision. The advanced and powerful 3-D analysis system processes sensor data and
generates shape and measurement results for display in intuitive format.
※Optical Frequency Domain Reflectometory
●Sensor length:1∼50 meters
●Smallest increments:1mm
●Measurement cycle: A-Type ∼5Hz
B-Type 100Hz
●Minimum resolution: ±2μStrain ±0.2℃
●Measurement range: ±10,000μStrain
(Polyimide coated fiber)
Key functions
●3-D analysis
(typically displayed as 3-D
color contours)
●3-D shape mapping
●3-D dimensional
●2-D graphing
●3-D graphing
●Other analysis and
evaluation tools
(Gold coated fiber)
FBI-Gauge can be used in a wide range of industries.
Building construction
Industrial facilities
Fiber B eam I nves t igat ion
FBI-Gauge Features
Distributed strain measurement
Advantages of FBI-Gauge
Example of strain measurement with FBI-Gauge
■Supports line and surface observation, as well as
point observation.
■Extremely lightweight sensor
■Can be used in electromagnetic environments and
places where fire is strictly prohibited
■Sensor can be freely attached to fit different measurement conditions
■Single sensor capable of performing strain, temperature, and a variety of other measurements.
Thin optic fibers with a diameter of 155μm can be
set in extremely narrow gaps.
They are also ideal for measuring the strain of
curved surfaces. (Minimum bending radius=10mm)
Diameter of a coin:
18 mm
Strain gauge
10 mm
Reduce man-hours and cost of settings
Optic fibers attached to the upper and lower faces of an aluminum cantilever are used to measure strain distribution. The results are presented in graphical form in 5 mm increments. The optic fiber, which is the red line, is
mounted on the upper and lower faces of the cantilever . A standoff cable is used to connect the left-hand end of
the optic fiber on the upper face to the FBI-Gauge unit.
(The loop-back at the right-hand end is not attached.)
Diameter of the optic fiber sensor:
155 μm
Uses of FBI-Gauge
Load F
■Measuring the strain or temperature in an electromagnetic environment
■Measuring an object with multiple measurement
points that make it difficult to install the gauge
■Checking the temperature distribution of a tower
that is tens of meters in height
■Measuring the inside of narrow gaps
■Conducting measurements when the weight of
the connection cable for the strain gauge is too
①Upper face
Static load strain
③Lower face
①Upper face: positive strain associated with tension
②Loop-back section: no load, no strain
③Lower face: negative strain associated with compression
Distributed temperature measurement
As the photo to the left shows, there is a problem
with point measurement -- Tons of connection
cables are needed when there is a large number of
gauge channels. The use of lightweight optic fibers
is the perfect solution for conducting measurements across numerous channels.
Optic fibers are thin and lightweight, allowing you
to freely design a layout that fits your installation
needs. As the figure to right shows, installation in
the air makes it possible to visualize the temperature distribution in space.
FBI-Gauge uses a single optic fiber to
measure temperature, eliminating the
hassle of having to synchronize the
time across multiple measurement
positions. The optic fiber can also be
installed in narrow spaces or
stretched across a wide space,
thereby offering a high degree of freedom for installation in places that pose
problems for conventional systems.
Iced water
(0℃ approx.)
Hot water
(85℃ approx.)
LC/APC adaptor
Hot water (85℃) = + 55°
Room temperature (30℃) = 0°
optic fiber
FBI-Gauge measures temperature by
monitoring constriction of the optic
fiber due to heat.
The starting temperature is recorded
as a baseline, and changes in temperature are determined relative to
the baseline.
Temperatures relative to baseline
room temperature ( = 0°)
Iced water (0℃) = -30°
Change in temperature
Fiber B eam I nves t igat ion
Use of FBI-Gauge in the automotive industry
FBI-Gauge is a strain and temperature sensing system that uses optic fibers for the sensors. Measurements can performed continuously along the optic fiber, allowing for continuous line and surface observation over a wide area, as well as point observation. The sensor
part of the FBI-Gauge does not use electricity, which means the system can also be used in
an electromagnetic environment.
Measurement of temperature distribution around the seat
Measurement of temperature
distribution by the air conditioner
Provided by Honda R&D Co., LTD.
When optic fibers are densely attached at intervals of
several centimeters, the FBI-Gauge can output distributed results just like a CAE tool.
This setup is ideal for comparing the results of an outer
panel rigidity test with the CAE results.
Rigidity test of outer panel
A single optic fiber sensor allows for the simultaneous
measurement of various parts.
The use of a single fiber eliminates the need for time
synchronization and other tasks. Thus, the FBI-Gauge
can also be used to compare the timing of multiple parts.
Measurement of exhaust temperature distribution
Measurement of temperature
and strain of resin injection mold
Measurement of water jacket
Measurement of oil tank
Measurement of battery temperature
Rigidity test of white bodies
Measurement of intercooler temperature
Measurement of strain during welding
Measurement of temperature distribution on the radiator
Measurement of temperature distribution inside the engine room
The use of a single optical fiber sensor for measurements makes it possible to visualize heat accumulation,
temperature gradient, and other conditions. It allows for
the measurement of localized distribution, which cannot
be measured through the point observation of multiple
parts. This provides for a more detailed examination of
the cooling efficiency.
The sensor can also be set up to measure temperature
distribution in space. Unlike thermography, which only
shows temperature distribution on a surface, the FBIGauge shows distribution in space.
Measurement of bore deformation during bolt tightening process
With the traditional point observation, there was an
unavoidable gap in skill between skilled workers and
inexperienced workers. There was also the troublesome
of task of checking whether the sensor was attached to
the position where the strain is at its peak. Distribution
measurement with the FBI-Gauge allows you to not only
locate the peak strain afterwards, but also confirm the
strain gradient.
The FBI-Gauge is ideal for measuring strain of precision
parts, such as the bore and bearing at the time of bolt
tightening. The extremely thin size of the optic fiber
sensor (155 μm) allows it be installed in many different
In addition the use of a single fiber sensor to perform
measurements also allows for time synchronization,
making it possible to check changes in strain while the
bolt is being tightened.
Fiber B eam I nves t igat ion
Use of FBI-Gauge in industrial facilities
and in the construction industry
Measuring temperature distribution of the plant
Introduction of optical fiber sensing advances in field of plant, because it does not affected by outside electromagnetic noise. Especially, FBI-Gauge excels in high-resolution
measurement and be applied in wide range of the field that was not able to measure by the
conventional electricity-style measurement technique and thermography.
Measuring surface hot spots on generator stator
FBI-Gauge for hot spots
Optic fiber can be deployed over a
wide area, allowing line and plane measurement not supported with conventional thermocouples.
Temperature data can be generated in
chronological form, and used to detect
abnormalities relative to a defined
steady state.
Thermometry of the tower
It is effective for a heat excess
change measurement since a
startup to the driving state of
the plant.
Hot Spots
Danger Zone
Optic fiber is attached to stator surface
A single strand of optic fiber can identify
multiple hot spots per millimeter.
Continuous measurement along the length
of the optic fiber allows more sophisticated detection of abnormalities such as
rapid changes in temperature distribution,
as well as abnormalities in absolute temperature values.
Thermometry of the tank
Thermometry of the heat exchanger
The optical fiber is most suitable for long-term monitoring because the service life is relatively and never rust.
( Normalized : x/L)
Hot spot measurements
Crack elongation in concrete
Using FBI-Gauge for concrete load testing
Optic fiber on the upper and lower surfaces of the concrete slab is used to measure crack elongation under
repeated load. A single optic fiber generates measurements along a line and can therefore measure multiple cracks
at the same time.
Fiber stretches bonded on the
upper side
Fiber stretches bonded on the
lower side
The concrete slab is supported at both ends and downward load is
applied to the center section
Optic fiber is attached to the upper and lower surfaces of
the concrete slab
Checking the aging deterioration
attributed to strain caused by
installation of the equipment
Measurement of temperature
distribution in a heat exchanger
Measurement of crack
growth in concrete
Measurement of temperature
distribution in a building
Testing strain during
repeated loading
Measurement of temperature
distribution in large equipment
Fiber B eam I nves t igat ion
Post software
How it works
The FBI-Gauge comes with software that processes vast amount of measurement data obtained from the measuring
Normally, measurement data is output in three axes: values for longitudinal directions of the optic fiber, those for
time, and those for strain and temperature. Accordingly, its processing is highly complicated with ordinary spreadsheet software.
The FBI-Gauge comes with powerful post software which is capable of processing three-axis data. This software
permits quick processing for noise elimination, creation of 2D and 3D graphs, and handling of 3D visualization tool.
This permits conversion of the data into intuitive output results and easy-to-understand graphs.
About FBI-Gauge
FBI-Gauge is an optic sensing system that detects minute light reflections (known as Rayleigh scattering) produced
by glass molecules in an optic fiber subject to a variable wavelength laser beam (1,510∼1,570 nm).
Unique optic fiber fingerprints and frequency offset due to strain
3D visualization tool
Set up the optic fiber sensor three-dimensionally as you like, measure temperature and/or strain, and use this tool
to visualize the obtained data in 3D graphics. This will allow you to create a video showing the results, which makes
you feel as if you were seeing the actual object on site. The tool uses point group obtained from 3D CAD of the
object or 3D laser scanner to convert the strain and/or temperature into 3D contour graphics. This allows you to
check intuitively where the peak is and what the gradient is like.
FBI-Gauge being used
for measurement
Rayleigh scattering light distribution sensing system
Minute density variations occur in the glass molecules in optic fiber. These are uniquely different for every optic fiber.
The density variations cause discrepancies in the refractive index and these in turn govern the light wavelengths
subject to Rayleigh scattering. The sum total of density variations along the length of an optic fiber is known as the
optic fiber fingerprint, which effectively means that the same wavelength will always produce the same reflections
provided that the optic fiber remains intact. In the event of strain occurring on the optic fiber, the reflected wavelengths will be offset at that particular point. FBI-Gauge uses a before and after comparison of reflected light patterns
to determine the location and degree of strain at points along the optic fiber.
No strain
Rayleigh scattering in fiber
(optic fiber fingerprint with no strain)
Measurement of
strain distribution
during a steel pipe
strength test
Rayleigh scattering
Rayleigh scattered light λ
FBI-Gauge can be used in combination with 3D laser measurement to produce
photograph-like report of measurement results.
Incident light λ
Filtering functions
Key functions
●3D analysis (typically displayed as 3D color contours)
●3D dimensional measurement
●2D graphing
●3D graphing
●Filtering functions
●Other analysis and evaluation tools
FBI-Gauge accuracy
Comparison with Extensometer and Strain gauge
In this example, we compare an extensometer and
strain gauge in a tensile test on a test piece. The extensometer and strain gauge generate results at the same
degree of precision. While the extensometer and strain
gauge use a single sensor at a single location, optic
fiber enables continuous measurement over the entire
fiber length.
The FBI-Gauge comes with functions for processing noise, which is generated frequently in optical
measurement, and detaching only necessary parts.
This enables quick processing of 3-axis data,
which is difficult with spreadsheet software.
FBI-Gauge detects reflected light in the form of Rayleigh
scattering in the optic fiber.
Scattering normally refers to random dispersion of light
caused by collisions with particles such as molecules in
the air. The phenomenon known as Rayleigh scattering is
associated with very small particles of the order of 10%
of the light wavelength. A brilliant blue sky is the result of
Rayleigh scattering of sunlight due to molecules in the air.
Rayleigh scattering in optic fiber, meanwhile, is caused by
collisions with glass molecules.
The data from the FBI-Gauge is highly consistent with the
extensometer and strain gauge observations.
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