presentation ph d

Innovative fiber optic sensors: from theory to applications

Daniele Tosi

PhD presentationElectronics Engineering2008-2009

Overview

Sensor networks market

Optical fiber sensors

Grating sensors

Low-cost solutions

Principles

Processing

Results

Potential

Daniele Tosi, [email protected]

Focus

Daniele Tosi - [email protected]

Sensor for measurement of mechanical and physical parameters• Direct: strain, vibrations, temperature, ...

• Indirect: pressure, rotation, resonance, modes, level, ...

Network

Applications

Cost control

Near future scenario


VSWireless Sensor Networks Fiber Optic Sensors

Market size


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Wireless

Optic

Global market

Market growth

Market size


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51% 49%Revenues

# units

WSNFOS

30%

70%

10%

90%

5%

95%

2008 2011

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Market size


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TelecomSensors

$6.2B

$335MWi-fi Sensors

$320M

$60B

Near future scenarioC

ost

TargetGen. Spec.

H

L

WSN


FOS

Differentiation


FOS WSN

Size ∅ <1mm 6x4x3 cm

Immunity Fiber immune to EMI

Active and passive interference

Distribution Distrib. + multiplex + punctual

PunctualSlow multiplex

Attenuation 0.2 dB/kmRemote sensing

WiLD < 1kmSmall cover area

FOS


Sensitivity

Cost$100 $1k $10k $100k $1M

10 pm

1 nm

100 nm

10 µm

1 mm POF

Doppler/TOF

Active fibers

Raman/Brillouin

CCD/imaging

Interferometry

FOS


28%

42%

Research papers

Revenues

Sensitivity

Cost$100 $1k $10k $100k $1M

10 pm

1 nm

100 nm

10 µm

1 mm POF

Doppler/TOF

Active fibers

Raman/Brillouin

CCD/imaging

Interferometry

FBG

FBG principles


FBG ➙ refractive index modulation inside the core of an optical fiber - wavelength/selective

FBG principles


Modulation period sensitive to:- mechanical strain- thermal expansion

Strain

Temperature

Λ

Λ

FBG principles


Peak

wav

elen

gth

(nm

)

Strain (με)

1 pm/µε10 pm/°C{

ΔL/L

FBG principles


Peak

wav

elen

gth

(nm

)

Strain (με)

1 pm/µε10 pm/°C{

➙ Temperature compensation

ΔL/L

FBG sensors


SourceReceiver

FBG arrays

...Coupling

?

FBG sensors


SourceReceiver

FBG arrays

...

?Coupling

Intensity detection


SourceReceiver

FBG arrays

...Coupling

FBG sensors


Sensitivity

Cost$1k $10k $100k $1M

<<1nm

100nm

1nm

Interferometry

FBG analyzer

Active fibers

Optical spectrum

Scanning filter

Intensitybased

Applications

• performance

• environment

• immunity

• safety

• invasiveness


Applications


35%

22%

15%

13%

7%3%

2%2%

Remote structuresSmart structuresSecurityIndustrial processSeismicAerospaceMilitaryMedical

FBG sensors


Cos

t

TargetGen. Spec.

H

L

WSN

FOS

Matched FBGs


Sensing Fixed

∫(·) ➥ power meter

Intensity modulation

Matched FBGs


Matched FBGs


0.18 mV/µε

320 µε

Matched laser


Matched laser


Backreflection

Matched laser


-150 -50 50 150

1

2

3

4

5

6

Strain

Volta

ge (V

)

60µε

10 mV/µε

1 mV/µε

FBGA


Commercial FBGA

Performances

M. FBGs M. Laser FBGA

Sensitivity ✓✓ ✓✓✓✓✓ ✓✓

Resolution ✓✓✓✓✓ ✓✓✓✓✓ ✓✓

Range ✓✓✓✓ ✓✓ ✓✓✓

# Sensors ✓✓✓ ✓✓ ✓✓✓✓✓

Stability ✓✓✓ ✓ ✓✓✓✓✓


Performances

M. FBGs M. Laser FBGA

Sensitivity ✓✓ ✓✓✓✓✓ ✓✓

Resolution ✓✓✓✓✓ ✓✓✓✓✓ ✓✓

Range ✓✓✓✓ ✓✓✓ ✓✓

# Sensors ✓✓✓ ✓✓ ✓✓✓✓✓

Stability ✓✓✓ ✓ ✓✓✓✓✓


Dynamic

Performances

Perform. Optical

Min SNR -10 dB

Sensitivity 800 nε

RMSE 2.2 µε

Overhead 0%


Signal processing


Sensitivity

Cost$1k $10k $100k $1M

<<1nm

100nm

1nm

Interferometry

FBG analyzer

Active fibers

Optical spectrum

Scanning filter

Intensitybased

SP

Signal processing


f/3kHzμε

PSD(dB)

D. Tosi, M. Olivero, G. Perrone, “Self-mixing based interrogation techniques for high-reflectivity fibre Bragg grating sensors”, Electronic Letters, vol. 44, 2008.

Time(s)

Aut

ocor

rela

tion(

a.u.

)

Noise properties - FBG backreflection

Signal processing


Adaptive filter - RLS 40 taps

Training

Acquired

Filtered

Reference

Signal processing


Adaptive filter - RLS 40 taps

Noise filtering

Acquired

Filtered

Reference

14 dB

Signal processing


Capon power spectral density estimatorJ. Capon, “High-resolution frequency-wavenumber spectrum analysis”, Proc. IEEE, vol. 57, 1969.

FFT Param. Capon

SNR -10 dB <-40 dB -25 dB

Resolution 1/N ~<1/N Unlimited

Properties None Required Adaptive

Signal processing


Capon power spectral density estimatorJ. Capon, “High-resolution frequency-wavenumber spectrum analysis”, Proc. IEEE, vol. 57, 1969.

FFT Param. Capon

SNR -10 dB <-40 dB -25 dB

Resolution 1/N ~<1/N Unlimited

Properties None Required Adaptive15 dB

Performances

Perform. Optical Optical + SP

Min SNR -10 dB -39 dB

Sensitivity 800 nε 5.6 nε

RMSE 2.2 µε 0.4 µε

Overhead 0% <1%


Setup


Climaticchamber

Strain

Circuit

DAQ

Setup


Temperature


Climatic chamber Outdoor

Temperature


Climatic chamber Outdoor

➙ Temperature compensation

Vibrations


Aluminum bar

Vibrations


POF sensorFBG

Surface wall

13 dB

Vibrations


Wooden board

27.1 Hz

Setup


Acquisition

Laser/TEC

WVF generator

Matlab sound

DAQ card FBG

Setup


Speaker Receiver

FBG

Voice


Voice recognition


Input

FBG

Voice recognition


Cepstrum ➙ FFT[Capon(voice)]

Metronome


www. metronomeonline.com

144 bpm112 bpm92 bpm

Heartbeat


Criticalities:- FBG positioning- signal processing

69.9bpm

Potential


35%

22%

15%

13%

7%3%

2%2%

Remote structuresSmart structuresSecurityIndustrial processSeismicAerospaceMilitaryMedical

Potential


35%

22%

15%

13%

7%3%

2%2%

Smart structures

Distributed sensor networksFew sensing points, repeated

Potential


35%

22%

15%

13%

7%3%

2%2%

Remote sensingLower cost solutions

Remote structures

Potential


35%

22%

15%

13%

7%3%

2%

2%Medical equipment

Increase smartness capabilityReplacement / redundancy

Potential


35%

22%15%

13%

7%3%

2%

2%

Niche applications in adjacent fields

Conclusion


• Fiber optic sensors market: trends and opportunities

• Applications range and requirements

• The proposed solutions - low cost FBG sensors

• The effect of signal processing

• Experimental results and potential developments

References


(1) D. Tosi, M. Olivero, G. Perrone, “Dynamic strain measurement system with fiber Bragg gratings and noise mitigation techniques”, Measurement Science and Technology, vol. 20, 2009.

(2) D. Tosi, M. Olivero, G. Perrone, “A low-cost fiber Bragg grating vibro-acoustic sensor for voice and heartbeat detection”, Applied Optics, vol. 47, 2008.

(3) D. Tosi, M. Olivero, G. Perrone, “Self-mixing based interrogation techniques for high-reflectivity fibre Bragg grating sensors”, Electronic Letters, vol. 44, 2008.

(4) D. Tosi, M. Olivero, G. Perrone, “Broadband source-based interrogation scheme of fiber Bragg grating sensors for structural health monitoring”, Key Engineering Materials, vol. 347, 2007.

(5) D. Tosi, M. Olivero, G. Perrone, “Optical microphone with fiber Bragg gratings and signal processing techniques”, Proc. SPIE, vol. 7098, 2008.

(6) D. Tosi, M. Olivero, G. Perrone, “Low-cost fiber Bragg grating-based static and dynamic strain system for structural monitoring”, Proc. SPIE, vol. 7098, 2008.

References


(7) Y. J. Rao, “In-fibre Bragg grating sensors”, Measurement Science and Technology, vol. 8, 1997.

(8) A. Othonos, K. Kalli, Fiber Bragg Gratings: Fundamentals and Applications in Telecommunications and Sensing, Artech House, 1999.

(9) W. W. Morey, “Distributed fibre grating sensors”, Proc. OFS Conference, 1997(10) F. A. Bezombes, M. J. Lalor, D. R. Burton, “Contact microphone using optical fibre

Bragg grating technology”, J. Phys. Conf. Ser., vol. 76, 2007.(11) A. Zaknich, Principles of Adaptive Filters and Self-Learning Systems, Springer, 2000.(12) J. Capon, “High-resolution frequency-wavenumber spectrum analysis”, Proc. IEEE,

vol. 57, 1969.(13) D. B. Huff, M. S. Lebby, “Fiber optic sensing technology: emerging markets and

trends”, Proc. SPIE, vol. 6619, 2007.(14) www.smartech.ch(15) www.bayspec.com (16) www.xbow.com

http://www.smartech.ch

http://www.smartech.ch

http://www.oceanoptics.com

http://www.oceanoptics.com

http://www.xbow.com

http://www.xbow.com

Acknowledgments


Julia GillardTracy HarrisSebastian Sabogal

Gaetano PellicanoBarbara PizzellaMaria Grazia Quieti

Armen Berjikly

Jake Wall

Guido Perrone

Massimo Olivero

Renato Orta

Alberto Vallan

Ivo Montrosset

Francesco Profumo

Claudio Maccone

+ others...

Antonio StrumiaSilvio Abrate

Barry PosnerKevin HolmesNick KurnsTerri GriffithMary Furlong

John CanningMattias AslundKevin CookMike Stevenson

EndThank you for your interest

Spectral response


Matched laser


Signal processing


Data modellingRMSE reconstruction:

11.4με ➙ 0.32με

(6 iterations)

D. Tosi, M. Olivero, G. Perrone, “Dynamic strain measurement system with fiber Bragg gratings and noise mitigation techniques”, Measurement Science and Technology, vol. 20, 2009.

15 dB

FBG inscription


Matched FBGs


Matched FBGs


∫(·)

Matched FBGs


∫(·)

Power(strain)

presentation ph d

Business

market growthmarket

future scenariohfoscostwsnl

innovative ber opticsensors

physical parameters

measurement of mechanical

telecomsensors wi

global marketrevenues

differentiation foswsnsize