S.Kumaresh M.Sabareesh and Vigneshwar11Department of Electronics Engineering, Anna

University, Madras Institute of Technology, Chennai, Tamil Nadu

Abstract

• To differentiate single and multi mode fiber optic cables.

• Analysis is done by using image processing in Mat Lab.

Electrical sensors

• Advantages : (a) Low cost (b) Flexible• Disadvantages : (a) Not accurate. (b) Inefficient.

Fiber Optic Sensors• Advantages : (a) Efficient (b) Accurate• Disadvantage : (a) High Cost

Main Contribution

• Stress and intensity of the light wave.• Image patterns (diffraction) are obtained

are processed in Mat Lab to obtain the corresponding intensity plot.

• By this method the deterioration of the light wave and power spectrum of intensity in the fiber optic cable is analyzed to differentiate between single and multimode fiber.

Experimental setup• A Single mode fiber of length 100m is

used here.• Ends are cleaned of dust using isopropyl

alcohol.• Mounted on an optical rail and in a

microscope. • A pen laser is mounted on the other end of

the optical rail bridge.

Continued• The distance between pen laser and the

optical fiber is adjusted till the line of sight between them is established.

• The dispersion pattern is observed through microscope.

Estimation of output

• The 3 dimensional matrix is converted into 2 dimensional matrix.

• The intensity pattern of the same is obtained which is normalized.

• So as to eliminate the noise and interference.

Experimental setup for measuring the intensity

Software module• Dispersion pattern is fed to a microscope using a web camera.• Obtained image is processed using Matlab• Its size is 240*320*3.• The resultant image is normalized to

analyze.

Normalized intensity pattern of single and multi mode fiber

Analysis• From the Normalized intensity plot :: If distance between two peaks = zero (a) Then it is single mode. ::Else (b) Then it is Multimode.

2-D intensity plot for 120th row and elements from 1to 320(Horizontal

Section)

2-D intensity plot for 170th column and elements from 1to 240(Vertical

Section)

ALGORITHM(1) Start by normalizing (a) Horizontal (b) Vertical(2) Count and measure the number of peaks(3) Threshold (Tp) (a) Set it to 30% (b) Count for the min distance.

(4) Is Tp>30% Increment L Else Increment K(5) Repeat for distance(6) If K=L and Tp>30% Single mode Else Multi mode

Conclusion• The Experiment can be done by (a) Using a laser light source. (b) A DSP processor.

Acknowledgement• Thanking to Dr. M.Ganesh Madan for

providing RF lab for this project.• Also for the event organizer for providing

us the opportunity.

Reference• A Course of Experiments with He-Ne Laser by R. S.

Sirohi• Fundamentals of Fiber Lasers and Fiber Amplifiers by

Ter Mikirtychev, Vartan• ‘Optical Fiber Sensors: A Versatile technology Platform

for Sensing’ by Bishnu P.Pal from the journal of Indian Institute of science.

• Strain and temperature measurement with fiber optic sensors by Regis J. Van Steenkiste

Thank you