1. Diaphragm Etching in Extrinsic Fabry-Perot
InterferometricFiber Optic Pressure Sensors[CLEO - Europe,
2013]Sven Poeggel, Daniele Tosi, Gabriel Leen, Elfed
LewisUniversity of Limerick, IrelandOptical Fibre Sensors Research
Centre (OFSRC)
2. Extrinsic FPInterferometerDaniele Tosi - Optical Fibre
Sensors Research Centre (OFSRC) - University of LimerickEFPI:
Fiber-optic Fabry-Perot interferometric sensor based on all-silica
glass structure: (1) launch fiber, (2) diaphragm, (3)
capillaryCapillaryLaunch SMfiberDiaphragmMM fiberAIR-GAPdL
3. dDaniele Tosi - Optical Fibre Sensors Research Centre
(OFSRC) - University of LimerickEFPI principleL
4. PressureL0 - Sp PDaniele Tosi - Optical Fibre Sensors
Research Centre (OFSRC) - University of LimerickEFPI
principleL
5. White light systemASE sourceASE
sourceSpectrometerSpectrometer1530-1600 nm1520-1596 nm
CouplerCoupler3 dB1x4
switchServerServerEFPIEFPIEFPIDAQDAQ(LabVIEW)(LabVIEW)Daniele Tosi
- Optical Fibre Sensors Research Centre (OFSRC) - University of
LimerickS pre-loadingpre-loadingEFPId estimationOnline QAHF
bath(argon-ion source)
6. SensitivityDaniele Tosi - Optical Fibre Sensors Research
Centre (OFSRC) - University of Limerickd = diaphragm thicknessa =
fiber inner diameterE = Possons ratio = Youngs modulussP =3(1
)2a416Ed3
7. SensitivityDaniele Tosi - Optical Fibre Sensors Research
Centre (OFSRC) - University of Limerickd = diaphragm thicknessa =
fiber inner diameterE = Possons ratio = Youngs
modulusTrade-offTiltFlatnessProblem:- etch the diaphragm to lowest
d- preserve air-gap sealing and FPI- independently on etching
speed
8. Wet etchingDaniele Tosi - Optical Fibre Sensors Research
Centre (OFSRC) - University of LimerickHydrofluoric acid (HF),
5-48%- Low BOM cost- Easy setup fume hood- Speed/concentration-
Chemically dangerous- Non-constant rate- Remove residual HF
9. Dry etchingDaniele Tosi - Optical Fibre Sensors Research
Centre (OFSRC) - University of Limerick- Multiple probe etching-
Etching rate ~constant- Dry, chemical-free- Preserve surface
quality- ExpensiveHigh power argon-ion etchingFemtosecond laser
etching~mm/s etching rate!
10. SimulationDaniele Tosi - Optical Fibre Sensors Research
Centre (OFSRC) - University of LimerickEtching rate:period = 0.495
mSpectrum (as on spectrometer)Q-point vs diaphragm length ( m)
11. Real-time dataDaniele Tosi - Optical Fibre Sensors Research
Centre (OFSRC) - University of LimerickAcceleratedetching in
HF48%Breakpoint
12. QA analysisDaniele Tosi - Optical Fibre Sensors Research
Centre (OFSRC) - University of LimerickLow-quality
probeHigh-quality probe
13. Pressure testDaniele Tosi - Optical Fibre Sensors Research
Centre (OFSRC) - University of Limerick18pm/mmHgSP = 2.3
nm/kPaAccuracy ~0.4 mmHg
14. Daniele Tosi - Optical Fibre Sensors Research Centre -
project portfolio - UL2013ConclusionsOptimization of EFPI
sensitivity for eachindividual sensorAchievement of 1-10 nm/kPa
sensitivity,leading to accuracy below 1 mmHgResults independent on
air-gap length, etchingtype and speed, geometryQA > 70% for
maximum sensitivity
15. AcknowledgmentsDaniele Tosi - Optical Fibre Sensors
Research Centre (OFSRC) - University of LimerickResearch support
Financial supportUL, Material and SurfaceScience InstituteScience
Foundation Ireland(RFP/ECE2898)UL, Chemical andEnvironmental
ScienceEnterprise Ireland (IP-2012-0166-Y)Galway-Mayo Institute
ofTechnologyFP7-People Marie Curie(299985 Probesens)