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Fiber Optics Presentation

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Group presentation for Signal Processing and Smart Structures Technology Class

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Fiber Optics Presentation

1. 1. Fiber optic sensors in sHM<br />UC Davis <br />ECI 223<br />Aileen vandenberg<br />Randy Presleigh<br />April 18, 2011<br />
2. 2. Introduction to FOS<br />Fiber optic technology history<br />Two basic classes of sensors:<br /> 1) Extrinsic<br /> Hybrid<br /> 2) Intrinsic<br /> All Fiber<br />
3. 3. Fiber optic sensors in SHM<br />Four potential functions:<br />Monitoring external manufacturing process parameters<br />Embedded sensors, non-destructive evaluation<br />Serve as data-link network to support other SHM systems<br />Compliment performance monitoring / control systems <br />
4. 4. Physics of Optical Fibers<br />Index of Refraction<br />The ratio of the speed of light, c, in a vacuum to the speed of light, v, in a material.<br />Notes<br /><ul><li>n ≥1
5. 5. A higher refractive index indicates light travels slower through the medium.</li></ul> <br />n = 𝐶𝑣<br /> <br />The Law of Reflection<br />The angle of reflectionis equal to the angle of incidence.<br />The Law of Refraction, a.k.a. Snell’s Law<br />n1 sin θ1 = n2 sin θ2<br />
6. 6. Physics of Optical Fibers<br />Total Internal Reflection<br />When the angle of incidence is greater than the critical angle.<br />The Critical Angle of Incidence<br />When the angle of refraction is equal to 90°.<br />Principal of fiber optics<br />
7. 7. Basics of an Optical Fiber<br />Components of optical fiber<br />Types of fibers<br />To achieve total internal reflection, ncladding < ncore<br />Numerical Aperture<br />Describes a range of angles the fiber can accept or transmit light with little loss. <br />Note: This is for a multi-mode, step-index fiber.<br />
8. 8. Fabrication of Optical Fibers<br />Step 1: Materials<br /><ul><li>Glass (e.g. SiO2)
9. 9. Plastic (e.g. polysterene)
10. 10. Doping Products (e.g. germanium)
11. 11. Increase or decrease index of refraction
12. 12. To change magnetic, optical, or electric properties</li></li></ul><li>Fabrication of Optical fibers<br />Step 2: Fabrication Process<br />Preform Process<br /><ul><li>Preforms are fabricated using a variety of vapor deposition processes.
13. 13. The fiber in drawn onto a spool.</li></ul>Direct Process<br />Melt or rod forms of the core and the cladding are combined directly to form the fiber.<br />Note: This process is good for a multi-mode, step-index fiber with a larger NA at low cost.<br />
14. 14. Optical Fiber Sensor Systems<br />Optical Fiber Sensor<br />Light source<br />Light Detector<br />Electronic Processing Equipment<br />Mechanisms for sensing<br /><ul><li>Intensity based
15. 15. Power output changes due to a change in the environment.
16. 16. Evanescent field based
17. 17. Interaction with the cladding alters the fiber wavelength modes.
18. 18. Bragg-Grating
19. 19. Variations in the refractive index of the core changes the output signal.
20. 20. Surface Plasmon Resonance
21. 21. Detection of surface waves that travel parallel to fiber.
22. 22. A combination of these techniques</li></li></ul><li>fos performance attributes<br />Advantages over conventional electronic sensors: <br /> 1) Silica based material<br /> 2) Multi-plexing<br /> 3) Cost <br />Limitations / challenges of FOS<br />In general, have a rugged, high band-with, low cost system.<br />
23. 23. fos performance attributes<br />Sensor spatial distribution resolution<br />1) Discrete point<br /> Ex: Fiber grating<br />strain gauge <br />2) Integrated <br /> Ex: Long gauge fiber <br />
24. 24. fos performance attributes<br />Sensor spatial distribution resolution<br />3) Quasi-distributed<br /> Ex: Series of fiber<br />grating strain gages<br />4) Distributed<br /> Ex: Temp sensor<br />along building face<br />
25. 25. Applications of Optical Fiber Sensors<br />Corrosion Sensing<br />Sensor head<br />Dope with fluorescent products<br />
26. 26. Strain Sensing<br />Confederation Bridge in Canada<br />- Service life / environment<br />- Embedded FBG sensors<br /> - Measure strain in concrete<br />
27. 27. Conclusion and Questions<br />Simple and rugged<br />Costs<br />Versatile<br /> QUESTIONS ?<br /> Fiber optic afro?<br />
28. 28. References<br />1. Adding dopants to a fiber to change or add characteristics. [cited 2011 April 15]; Available from: http://www.paradigmoptics.com/pof/custompof.html.<br />2. Fabrication of an Optical Fibre. 30 May, 1997 [cited 2011 April 15]; Available from: http://www.vislab.uq.edu.au/photonics/fibres.<br />3. AL-Zu’bi, R.e. Optical Fiber Fabrication & Measurements. [cited 2011 April 15]; Available from: http://dar.ju.edu.jo/mansour/optical/Fiber%20Fabrication%20and%20measurments.htm.<br />4. S. C. Warren-Smith, H. Ebendorff-Heidepriem, S. Afshar, G. McAdam, C. Davis, and T.M. Monro, Corrosion Sensing of Aluminum Alloys Using Exposed Core Microstructured Optical Fibers, Institute of Materials Engineering Australasia, 2009.<br />5. Overview of Fiber Optic Sensors. [cited 2011 April 15]; Available from: http://www.bluerr.com/images/Overview_of_FOS2.pdf.<br />6. Fiber Optics. [cited 2011 April 16]; Available from: http://www.eliteavi.com/blog/dallasaudio-video-integration/fiber-optics/.<br />7. José Miguel López-Higuera, Luis Rodriguez Cobo, Antonio QuintelaIncera, and Adolfo Cobo, Fiber Optic Sensors in Structural Health Monitoring, Journal of Lightwave Technology, Vol. 29, NO. 4, FEBRUARY 15, 2011<br />