An optical liquid level sensor based on polarization-maintaining fiber

modal interferometer

By: Sasicha Pornlert 6/6 No.5Advisor: Kitisak Boonkham

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Huaping G., Haifeng S., Sulei Z., Kai N., & Xinyong D.

SEMINAR

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Outline

• Introduction– Polarization– Polarization-maintaining fiber (PMF)

• Experiment & Principle– Diagram of experiment– Theory

• Result & Discussion• Conclusion• Reference• Acknowledgement

INTRODUCTION

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Introduction

IndustryHousehold

AgricultureChemical

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Liquid Level sensor

Toxic FlammableBenefit For

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Polarization

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http://catalog.flatworldknowledge.com/bookhub/reader/1790?e=averill_1.0-ch24_s02

Polarization-maintaining Fiber (PMF)

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http://www.physicsclassroom.com/class/light/Lesson-1/Polarization

An Polarization-maintaining Fiber Modal Interferometer

• Prevent electromagnetic interference• High sensitivity• Small size• Easy to fabricate• Robustness• Cheaper

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EXPERIMENT & PRINCIPLE

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The Schematic Diagram of the Proposed Sensor

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L

L’

BBS

OSA

The Schematic Diagram of the Proposed Sensor

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Cladding

Core

Single Mode Fiber (SMF)

Polarization- maintaining Fiber (PMF)

Splicer

L

Theory

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Path difference expressed by

Wavelength Shift can satisfied by

(1)

From equation (1), it can obtain that

is the resonant dip wavelength

Where

is an integerm

Theory

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When the test liquid immersed the portion of sensor

L

L’Liquid Level

Length of PMF

is the different of liquid and cladding index

RESULT & DISCUSSION

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Graph of Transmission Spectra of Level Sensor in Brine with the Reflective index of 1.363

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Good Visibility

Graph of Transmission Spectra under different Level of Brine

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Red Shift

Graph of Relation between Liquid Level and Wavelength Shift with different Reflective Indices

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Sensitivity isSlope

Graph of Relation between Liquid Level and Wavelength Shift with different Length of PMF

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Graph of Relation between Temperature and Wavelength Shift

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CONCLUSION

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Conclusion

• Wavelength shift is almost linearly proportional to the change of liquid level

• The sensitivity increases with the refractive index of liquid

• The shorter the PMF is the higher sensitivity is• Temperature affect the experiment

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An optical liquid level sensor based on polarization-maintaining fiber modal interferometer

• Easy fabricate• Structural stability• High sensitivity

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Another interesting way for measuring liquid level

ReferenceHuaping, G., Haifeng, S., Sulei, Z., Kai, N., & Xinyong, D. (2013). An optical

liquid level sensor based on polarization-maintaining fiber modal interferometer. Eslevier, 205 (2014), 204-207

Li, L. C., Xia, L., Xie, Z. H., & Liu, D. M., All-fiber Mach–Zehnder interferometers for sensing applications, Opt. Expr. 20 (2012), 11109–11120.

Antonio-Lopez, J. E., Sanchez-Mondragon, J. J., LiKamWa, P., & May-Arrioja, D. A., Fiber-optic sensor for liquid level measurement, Opt. Lett. 36 (2011), 3425–3427.

Geng, Y. F., Li, X. J., Tan, X. L., Deng, Y. L., & Yu, Y. Q. High-sensitivity Mach–Zehnder interferometric temperature fiber sensor based on a waist-enlarged fusion bitaper, IEEE Sens. J. 11 (2011), 2891–2894.

Fusion splicing. Retrieved April 14, 2013 from the Wikipedia: http://en.wikipedia.org/wiki/Fusion_splicing

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ReferenceLevel sensor. Retrieved May 20, 2014 from the Wikipedia:

http://en.wikipedia.org/wiki/Level_sensor#Sensors_for_both_point_level_detection_or_continuous_monitoring

Polarization-maintaining optical fiber. Retrieved July 5, 2012 from the Wikipedia: http://en.wikipedia.org/wiki/Polarization-maintaining_optical_fiber

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Acknowledgement

Thanks to Mr. Kitisak Boonkham for advising and encouraging

me to present this knowledge for benefit to everyone in here.

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Thank you allQuestion