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SmartScan FBG InterrogatorFeatures and Benefits

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SmartScan Description

• SmartScan is a dynamic interrogator for use with fibre Bragg grating (FBG) sensors

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SmartScan OperationIt contains an electronically tuneable

laser which emits light at 400 discrete wavelengths across a 40 nm

bandwidth on multiple fibres

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SmartScan Operation

Optical detectors inside SmartScan then measure the light reflected from each

fibre at each of the 400 laser wavelengths, so building up a spectrum

of the connected FBGs

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Zooming in on one FBG shows the laser tuning points (seen as dots)

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SmartScan Operation

• The peak wavelength of every connected FBG is calculated by SmartScan’s high-speed electronics at the instrument sample rate of 2.5 kHz.

• This allows dynamic events to be captured…

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A dynamic strain event sampled at 2.5 kHz

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SmartScan Unique Selling Points

Robustness:•SmartScan’s light source is a widelytuneable semiconductor laser withthe active optical elements contained in a tiny monolithic chip, just a few millimetres long. All other components are passive optical and electronic components. This makes SmartScan very robust and more tolerant of thermal and mechanical influences than swept laser or spectrometer based instruments.•The instrumentation has demonstrated its robustness in several military flight trials…

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SmartScan Unique Selling Points

Robustness:•A SmartScan variant was prepared for flight trials, and passed the following pre-flight ground tests:

Parameter Tested Capability

Operating Temperature -15 to +55 °C

EMC: Conducted susceptibility and conducted emissions

MIL-STD-416Eparts CS101 and CS 102

Acceleration Vertical-Z (9g)Lateral-X&Y (2.5g)

Vibration 0.15 (g2/Hz) 0-100Hz0.10 (g2/Hz) 100-1000Hz

Acoustic Noise MIL-STD-810F

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SmartScan Unique Selling Points

• It then successfully completed a series of high and low altitude flights on a BAe Systems Hawk, and was assessed to have reached a technology readiness level of 7 out of 9

Robustness:

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SmartScan Unique Selling Points

Robustness:•The mean time before failure (MTBF) prediction of the current, commercial grade SmartScan is given below:

•Future, enhanced environment variants are expected to offer extended MTBF

Environment considered MTBF Prediction

Ground, Fixed, GF 40oC 4.2 years

Ground, Benign, GB 40oC 16.1 yearsBy parts count reliability method per MIL_HDBK_217F

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SmartScan Unique Selling Points

Speed:•SmartScan’s agile laser and custom tuning circuits allow data rates of 25 kHz for sequentially sampled FBGs. This makes high speed vibration and other such analyses possible with optical sensors.

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SmartScan Unique Selling PointsResolution:•SmartScan delivers sub-picometer resolution per sample at 2.5 kHz. This allows over-sampling and averaging to give extraordinary resolution.

Example Data Set: SmartScan reading 2mm FBG, 1550 nm, 70%R, 0.7nm FWHM

Data Averaging STDEV Resolution(pm)

STDEV Resolution (microstrain)

60s, raw data - 2.5 kHz 0.39 0.33

60s, 10 averages – 250 Hz 0.13 0.11

60s, 100 averages – 25 Hz 0.06 0.05

60s, 1000 averages – 2.5 Hz 0.04 0.03

Source data (6 MB) available to download

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SmartScan Unique Selling Points

Dynamic range:•SmartScan’s laser has a high output power, giving a 39 dB dynamic range which allows it to interrogate sensors tens of km away (for instance in a deep subsea well).•Sensor attenuation within this dynamic range is compensated by 9x3dB gain stages which are automatically set by the instrument.•Uniquely, SmartScan offers automatic per-sensor gain, such that if one or more sensors on a fibre suffer attenuation, they are individually amplified without affecting the other sensor gain settings

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SmartScan Summary

Below are the current SmartScan capabilities:Parameter Current Specification

Wavelength Range 40 nm

Number of fibres 1 to 4

Sensors per fibre Up to 16

Scan frequency 2.5 kHz all sensors simultaneouslyup to 25 kHz each sensor in turn

Resolution Typ ⅓ microstrain per sample standard deviation,reducing tenfold with averaging

Wavelength Stability 5 pm over operating temperature range of -15 to +55 °CMax 20 pm laser wavelength change over 25 years

Dynamic range 39 dB (27 dB attenuation before performance loss)9 automatic 3dB gain stages

Enclosure Standard for field use, 140 x 110 x 70mm, 0.9 kg

Comms Interface Ethernet

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SmartScan Development Roadmap

Below are future capabilities planned on the SmartScan development roadmap:Parameter Capability Target on Roadmap

Wavelength Range Increase to 80 nm ü done

Number of fibres 8, 16 ü done

Scan frequency 5 kHz all sensors simultaneouslyup to 50 kHz each sensor in turn

Enclosure and environmental

Re-packaging and qualification to suit requirements for:• Fixed and rotary wing aerospace deployment ü done

• Global field deployments• Deepwater subsea deployment

Comms Interface CANBus, ProfiBus etc ü done

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End

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