Abstract

A novel optical-fiber displacement sensor is proposed and demonstrated. It consists of a laser diode light source, an optical-fiber probe, and two photodetectors. The bundling of the probe is sectioned into three parts: a centrally positioned fiber in the bundle for illumination, the first-neighbor fibers for receiving (part I), and the remaining fibers for receiving (part II). The ratio of the difference to the sum of the output signals from the part I and the part II receiving fibers can eliminate the variation in the sensitivity of the sensor to reflectivity of the target. The performance of the sensor is geometrically analyzed. The working distance is determined by the distance from the centered illuminating fiber to the boundary between the part I and the part II receiving fibers. The experimental measurements made with three different reflectivity targets confirm that the sensor performance is independent of the three reflectivities, as predicted by the analysis.

© 1999 Optical Society of America

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References

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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
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    [CrossRef] [PubMed]
  7. A. Shimamoto, K. Tanaka, “Development of a depth controlling nanoindentation tester with subnanometer depth and submicro-newton load resolutions,” Rev. Sci. Instrum. 68, 3494–3503 (1997).
    [CrossRef]

1997

A. Shimamoto, K. Tanaka, “Development of a depth controlling nanoindentation tester with subnanometer depth and submicro-newton load resolutions,” Rev. Sci. Instrum. 68, 3494–3503 (1997).
[CrossRef]

1996

1995

1985

1979

Cook, R. O.

Frank, W. E.

W. E. Frank, “Detection and measurement device having a small flexible fiber transmission line,” U.S. patent3,273,447 (20September1966).

Goodman, G.

Hamm, C. W.

Johnson, M.

Kissinger, C. D.

C. D. Kissinger, “Fiber optic proximity probe,” U.S. patent3,327,584 (27June1967).

Shimamoto, A.

Tanaka, K.

Appl. Opt.

Rev. Sci. Instrum.

A. Shimamoto, K. Tanaka, “Development of a depth controlling nanoindentation tester with subnanometer depth and submicro-newton load resolutions,” Rev. Sci. Instrum. 68, 3494–3503 (1997).
[CrossRef]

Other

W. E. Frank, “Detection and measurement device having a small flexible fiber transmission line,” U.S. patent3,273,447 (20September1966).

C. D. Kissinger, “Fiber optic proximity probe,” U.S. patent3,327,584 (27June1967).

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Figures (8)

Fig. 1
Fig. 1

Schematic setup of the differential optical-fiber displacement sensor.

Fig. 2
Fig. 2

Schematic illustration of the differential optical-fiber displacement sensor.

Fig. 3
Fig. 3

(a) II - I, II + I versus k - 1 relationships, (b) Γ versus k - 1 relationships for two packing ratios.

Fig. 4
Fig. 4

versus N I relationships for two different packing ratios.

Fig. 5
Fig. 5

(a) Block diagram of the detection system in the differential optical-fiber displacement sensor, (b) the experimental setup for confirming the analysis and performance of the proposed method. See text for notation used.

Fig. 6
Fig. 6

P II - P I and P II + P I versus y relationships (upper panel), with Γ (lower panel) versus y relationships for a gold-coated glass target.

Fig. 7
Fig. 7

Influence of inclined angle of a light source.

Fig. 8
Fig. 8

Experimental P II - P I, P II + P I versus y relationships (upper panel) and Γ versus y relationship (lower panel) among three different targets. VTR, video tape recorder.

Equations (17)

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Cm,n=cm2+n2+mn1/2,
c=l/x0=2x0+2xc+xs/x0.
AIy, ϕ=6m+n=1Cm,n/c-1/2NI Am,ny, ϕ-m=1m=NI Am,0y, ϕ,
AIIy, ϕ=6Cm,n/c-1/2>NICm,n/c-1/2NII Am,ny, ϕ-m=NI+1m=NII Am,0y, ϕ.
k=2y tan ϕ/x0+1.
pϕ, y=pk=pin/2k2-4k+4k2
=pin/4k-42k,
PI(k)=K2ρPinp¯kA¯Ik,
PII(k)=K2ρPinp¯kA¯IIk,
VIk=FPIk,
VIIk=FPIIk.
Vdif=VII-VI=FK2ρPinp¯kAIIk-AIk,
Vsum=VII+VI=FK2ρPinp¯kAIIk+AIk.
Γ=PIIk-PIkPIIk+PIk=AIIk-AIkAIIk+AIk.
y¯wcNI+1/2.
S=2 tan ϕx0S¯=0.0390 μm-1.
N¯=NB=Q1Pmax+Q2Pmax21Sy0,

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