Pakanat Srijaroen 6105015 SCPY/B

Department of Physics, Faculty of Science, Mahidol University

Optical Fiber Bundle Displacement Sensors (OFBDS)

Application of OFBDS

1

Liquid level sensingThe sensing of surface roughness

OFBDS

Hang Zhou Yang. et al. (2014).

OFBDS

OutlinesIntroductionTheoretical modelSimulation

Experiment

Results

Discussion

Conclusion

2https://www.electronicsweekly.comhttps://global-sei.com/fttx/basicinfo/opticalfibernetworkwiringitems.html

Optical Fiber

3

Single fiber pair model

• Light source (S)

• Transmitting fiber (TF)

• Receiving fiber (RF)

• Photodetector (D)

Huimin Cao. et al. (2007).

4

Optical fiber bundle displacement sensors (OFBDS)

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5

Random (R)

Transmitting fiber (TF)

Receiving fiber (RF)

Concentric (C) Hemicircular (H)

Huimin Cao. et al. (2007).

Optical fiber bundle displacement sensors (OFBDS)

6

Hexagonal coordinates

(1,0)

(0,1)(-1,1)

(-1,0)

(0,-1) (1,-1)

(0,0)

(1,1)

(0,3)

Huimin Cao. et al. (2007).

Optical fiber bundle displacement sensors (OFBDS)

7

The distance between a and a is

Optical fiber bundle displacement sensors (OFBDS)

: center to center distance

Theoretical model

8

Single fiber pair model

Fiber bundle model

9

Single fiber pair modelTheoretical model :

Huimin Cao. et al. (2007).

Output light intensity distribution

• Light source (S)

• Transmitting fiber (TF)

• Receiving fiber (RF)

• Photodetector (D)

10

where : light power emitted from TF: effective radius of the output optical field

TFRF

Single fiber pair modelTheoretical model :

The intensity at the point is expressed by a modified Gauss function as

11

TFRF

Single fiber pair modelTheoretical model :

Note :

The intensity of reflected light ( )

???

11

TFRF

is the reflectivity of target surface

Single fiber pair modelTheoretical model :

Note :

The intensity of reflected light ( )

12

TFRF

Single fiber pair modelTheoretical model :

Note :

The intensity of reflected light ( )

is the reflectivity of target surface

13

Single fiber pair modelTheoretical model :

The received power is

pTF

RF

14

Single fiber pair modelTheoretical model :

The received power :

modulation function

: reflectivity of target surface

: light power emitted from TF

Theoretical model

15

Single fiber pair model

Fiber bundle model

16

Theoretical model : Fiber bundle model

The power received by the jth RF from the ith TF

The light power emitted from TF is

The total received power is

Theoretical model : Fiber bundle model

The total received power :

: distance between a and a

: reflectivity of target surface

: light power emitted from TF

: modulation function

17

modulation function :

18

Theoretical model : Fiber bundle model

Double circular (DC)

Concentric hemicircular (CH)

Concentric random (CR)

Hemicircular random (HR)

Transmitting fiber (TF)

Receiving fiber (RF)

DC CRCH HR

Huimin Cao. et al. (2007).

OFBDS with twin RF bundles

18

Theoretical model : Fiber bundle model

Double circular (DC)

Concentric hemicircular (CH)

Concentric random (CR)

Hemicircular random (HR)

Transmitting fiber (TF)

Receiving fiber (RF)

DC CRCH HR

The relative light power :

Huimin Cao. et al. (2007).

OFBDS with twin RF bundles

Simulation

19

CH CR DC HR

Huimin Cao. et al. (2007).

OFBDS with twin RF bundles

CI : inner circular RFCO : outer circular RF

DC – type has highest sensitivity

Simulation

19

CH CR DC HR

Huimin Cao. et al. (2007).

CI : inner circular RFCO : outer circular RF

OFBDS with twin RF bundles

DC – type has highest sensitivity

Experiment

20

Double circular (DC) - type

The root-mean-square (RMS) voltage

The relative RMS voltage

: current responsivity

: feedback resistance

: voltage gain: relative light power Huimin Cao. et al. (2007).

Results

21Huimin Cao. et al. (2007).

The theoretical curves vs the experimental results vs displacement

P1 : total received power

from RF-1 bundles

P2 : total received power

from RF-2 bundles: relative light power

Discussion :

22

The sensitivity of OFBDS

with single RF bundle

with twin RF bundles

The normalized sensitivity

Sensitivity

Huimin Cao. et al. (2007).

H : High

Z : ZeroL : Low

23

Discussion

24

Discussion

25

Discussion

26

Discussion

Application of OFBDS

27

Liquid level sensingThe sensing of surface roughness

Hang Zhou Yang. et al. (2014).

single RF bundle

twin RF bundles

No

rmal

ized

po

wer

(m

V)

single RF bundle

Conclusion

28

OFBDS containing one TF bundle and two RF bundles was created.

OFBDS containing one TF bundle and one RF bundle was still worked fine but it depends on reflectivity.

29

References

Cao, H., Chen, Y., Zhou, Z., & Zhang, G. (2007). Theoretical and experimental study on the optical fiber bundle displacement sensors. Sensors and Actuators A: Physical, 136(2), 580-587.

Yang, H. Z., Qiao, X. G., Luo, D., Lim, K. S., Chong, W., & Harun, S. W. (2014). A review of recent developed and applications of plastic fiber optic displacement sensors. Measurement, 48, 333-345.

Q&A

Numerical aperture (NA)

: Acceptance angle

https://www.pantechsolutions.net/blog/numerical-aperture-of-optical-fiber-cable/

https://slideplayer.com/slide/8979465/

CH CR DC HR

Huimin Cao. et al. (2007).

N. Sangeetha. et al. (2017).

Shot noise where : electron charge: equivalent noise bandwidth

Johnson noise where : Boltzmann constants

: temperature in K

Noise Equivalent Displacement (NED)

single receiving system

twin receiving system

: voltage gain: sensitivity of OFBDS

where

Resolution

Huimin Cao. et al. (2007).

Dynamic range (DR)

• Linear range (LR)• Noise equivalent displacement (NED)

Huimin Cao. et al. (2007).

Random (R)

Concentric (C)

Hemicircular (H)

Double circular (DC)

Concentric hemicircular (CH)

Concentric random (CR)

Hemicircular random (HR)

Transmitting fiber (TF)

Receiving fiber (RF)

Huimin Cao. et al. (2007).

The received power is

Huimin Cao. et al. (2007).

Huimin Cao. et al. (2007).

The distance from a fiber to the origin is

The distance between a and a is

1

R

r

c

r

c

g

Transmitting fiber (TF)

Receiving fiber (RF)

Random (R) - type

Optical fiber bundle displacement sensors (OFBDS)

Simulation

1R C HHuimin Cao. et al. (2007).

1

Integral model

Theoretical model : Fiber bundle model

m groups of different p

suppose

: distribution density of p

Huimin Cao. et al. (2007).

1

Integral model

Theoretical model : Fiber bundle model

1

Theoretical model : Fiber bundle model

Summation model

Integral model

Expanded model

Theoretical model : Fiber bundle model

: reflectivity of target surface

: light power emitted from TF

: modulation function

Summation model

The total received power is

1

???

Integral model

Theoretical model : Fiber bundle model

: reflectivity of target surface

: light power emitted from TF

: modulation function

Summation model

The total received power is

Integral model

1

1

Theoretical model : Fiber bundle model