Abstract

We present a novel noncontact optical method for absolute measurement of refractive index and thickness of optically transparent media. The method is based on a simple dual-confocal fiber-optic sensor design. It includes two independent confocal channels consisting of two identical apertureless fiber-optic-type confocal microscopes constructed by use of a single 2×2 fiber coupler. A geometrical-ray model is used to obtain the analytical dependence between the sample’s refractive index and its thickness. The measurement method provides high accuracy in spatially locating the specific imaging points that correspond to the backreflected intensity peaks of the confocal responses. Thus, a simultaneous measurement of the sample refractive index and thickness is achieved.

© 2002 Optical Society of America

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References

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  1. T. Corle and G. Kino, Confocal Scanning Optical Microscopy and Related Imaging Systems (Academic, San Diego, Calif., 1996).
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    [CrossRef]
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    [CrossRef] [PubMed]
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    [CrossRef]
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    [CrossRef]

2000 (2)

I. Ilev and R. Waynant, Rev. Sci. Instrum. 71, 4161 (2000).
[CrossRef]

H. Tiziani, M. Wegner, and D. Steudle, Opt. Eng. 39, 32 (2000).
[CrossRef]

1997 (2)

A. Gruber, A. Drabenstedt, C. Tietz, L. Fleury, J. Wrachtrup, and C. von Borczyskowski, Science 276, 2012 (1997).
[CrossRef]

M. Ohmi, T. Shiraishi, H. Tajiri, and M. Haruna, Opt. Rev. 4, 507 (1997).
[CrossRef]

1996 (1)

1995 (2)

1994 (1)

1991 (1)

1989 (1)

G. Kino and T. Corle, Phys. Today 42(9), 55 (1989).
[CrossRef]

1986 (1)

Bouma, E.

Brezinski, M.

Chou, G.

Corle, T.

G. Kino and T. Corle, Phys. Today 42(9), 55 (1989).
[CrossRef]

T. Corle and G. Kino, Confocal Scanning Optical Microscopy and Related Imaging Systems (Academic, San Diego, Calif., 1996).

Delaney, P.

Drabenstedt, A.

A. Gruber, A. Drabenstedt, C. Tietz, L. Fleury, J. Wrachtrup, and C. von Borczyskowski, Science 276, 2012 (1997).
[CrossRef]

Fleury, L.

A. Gruber, A. Drabenstedt, C. Tietz, L. Fleury, J. Wrachtrup, and C. von Borczyskowski, Science 276, 2012 (1997).
[CrossRef]

Fujimoto, J.

Fukano, T.

Gorle, T.

Gruber, A.

A. Gruber, A. Drabenstedt, C. Tietz, L. Fleury, J. Wrachtrup, and C. von Borczyskowski, Science 276, 2012 (1997).
[CrossRef]

Harris, M.

Haruna, M.

M. Ohmi, T. Shiraishi, H. Tajiri, and M. Haruna, Opt. Rev. 4, 507 (1997).
[CrossRef]

Hee, M.

Ilev, I.

I. Ilev and R. Waynant, Rev. Sci. Instrum. 71, 4161 (2000).
[CrossRef]

I. Ilev, Opt. Commun. 119, 513 (1995).
[CrossRef]

Kimura, S.

King, R.

Kino, G.

G. Kino and T. Corle, Phys. Today 42(9), 55 (1989).
[CrossRef]

T. Gorle, G. Chou, and G. Kino, Opt. Lett. 11, 770 (1986).
[CrossRef]

T. Corle and G. Kino, Confocal Scanning Optical Microscopy and Related Imaging Systems (Academic, San Diego, Calif., 1996).

Ohmi, M.

M. Ohmi, T. Shiraishi, H. Tajiri, and M. Haruna, Opt. Rev. 4, 507 (1997).
[CrossRef]

Shiraishi, T.

M. Ohmi, T. Shiraishi, H. Tajiri, and M. Haruna, Opt. Rev. 4, 507 (1997).
[CrossRef]

Southern, J.

Steudle, D.

H. Tiziani, M. Wegner, and D. Steudle, Opt. Eng. 39, 32 (2000).
[CrossRef]

Tajiri, H.

M. Ohmi, T. Shiraishi, H. Tajiri, and M. Haruna, Opt. Rev. 4, 507 (1997).
[CrossRef]

Tearney, G.

Tietz, C.

A. Gruber, A. Drabenstedt, C. Tietz, L. Fleury, J. Wrachtrup, and C. von Borczyskowski, Science 276, 2012 (1997).
[CrossRef]

Tiziani, H.

H. Tiziani, M. Wegner, and D. Steudle, Opt. Eng. 39, 32 (2000).
[CrossRef]

von Borczyskowski, C.

A. Gruber, A. Drabenstedt, C. Tietz, L. Fleury, J. Wrachtrup, and C. von Borczyskowski, Science 276, 2012 (1997).
[CrossRef]

Waynant, R.

I. Ilev and R. Waynant, Rev. Sci. Instrum. 71, 4161 (2000).
[CrossRef]

Wegner, M.

H. Tiziani, M. Wegner, and D. Steudle, Opt. Eng. 39, 32 (2000).
[CrossRef]

Wilson, T.

Wrachtrup, J.

A. Gruber, A. Drabenstedt, C. Tietz, L. Fleury, J. Wrachtrup, and C. von Borczyskowski, Science 276, 2012 (1997).
[CrossRef]

Yamaguchi, I.

Appl. Opt. (2)

Opt. Commun. (1)

I. Ilev, Opt. Commun. 119, 513 (1995).
[CrossRef]

Opt. Eng. (1)

H. Tiziani, M. Wegner, and D. Steudle, Opt. Eng. 39, 32 (2000).
[CrossRef]

Opt. Lett. (3)

Opt. Rev. (1)

M. Ohmi, T. Shiraishi, H. Tajiri, and M. Haruna, Opt. Rev. 4, 507 (1997).
[CrossRef]

Phys. Today (1)

G. Kino and T. Corle, Phys. Today 42(9), 55 (1989).
[CrossRef]

Rev. Sci. Instrum. (1)

I. Ilev and R. Waynant, Rev. Sci. Instrum. 71, 4161 (2000).
[CrossRef]

Science (1)

A. Gruber, A. Drabenstedt, C. Tietz, L. Fleury, J. Wrachtrup, and C. von Borczyskowski, Science 276, 2012 (1997).
[CrossRef]

Other (1)

T. Corle and G. Kino, Confocal Scanning Optical Microscopy and Related Imaging Systems (Academic, San Diego, Calif., 1996).

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Figures (3)

Fig. 1
Fig. 1

Experimental optical setup of the dual-confocal fiber-optic measurement method: laser, He–Ne laser (632.8 nm); O1, O2, confocal focusing objectives; CM1, CM2, first and second confocal microscopes, respectively; detector, precise digital powermeter.

Fig. 2
Fig. 2

Operating principle of the dual-confocal fiber-optic measurement method.

Fig. 3
Fig. 3

Typical experimental graphs of the dependence of the backreflectance confocal signals on the axial sample displacement.

Equations (3)

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ns sinθr=sinθi=NA,
ts tanθr=d tanθi.
ns=NA2+1-NA2ts/d21/2.

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