Abstract

A simple method based on total internal reflection is presented for measuring the refractive index of biological tissue. A narrow laser beam and a semicylindrical lens in contact with a tissue specimen are used in the experimental apparatus. The dependence of the internal reflectivity on the angle of incidence is measured to determine the critical angle and therefore the refractive index of tissue. The experimental results for several tissue samples show that the method is reliable and useful for studying tissue optics. The principal advantages of the method are its elimination of scattering effects, suitability to a small in vitro sample, and excellent accuracy.

© 1996 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. B. C. Wilson, “Modeling and measurements of light propagation in tissue for diagnostic and therapeutic applications,” in Laser Systems for Photobiology and Photomedicine, A. N. Chester, S. Martellucci, A. M. Scheggi, eds., Vol. 252 of NATO American Standards Institute Series (Plenum, New York, 1991), pp. 13–27.
    [CrossRef]
  2. L. O. Svaasand, C. J. Gomer, “Optics of tissue,” in Dosimetry of Laser Radiation in Medicine and Biology, Proc. Soc. Photo-Opt. Instrum. Eng. IS-5, 114–132 (1989).
  3. W. F. Cheong, S. A. Prahl, A. J. Welch, “A review of the optical properties of biological tissues,” IEEE J. Quantum Electron. 26, 2166–2185 (1990).
    [CrossRef]
  4. F. P. Bolin, L. E. Preuss, R. C. Taylor, R. J. Ference, “Refractive index of some mammalian tissues using a fiber optic cladding method,” Appl. Opt. 28, 2297–2303 (1989).
    [CrossRef] [PubMed]

1990

W. F. Cheong, S. A. Prahl, A. J. Welch, “A review of the optical properties of biological tissues,” IEEE J. Quantum Electron. 26, 2166–2185 (1990).
[CrossRef]

1989

F. P. Bolin, L. E. Preuss, R. C. Taylor, R. J. Ference, “Refractive index of some mammalian tissues using a fiber optic cladding method,” Appl. Opt. 28, 2297–2303 (1989).
[CrossRef] [PubMed]

L. O. Svaasand, C. J. Gomer, “Optics of tissue,” in Dosimetry of Laser Radiation in Medicine and Biology, Proc. Soc. Photo-Opt. Instrum. Eng. IS-5, 114–132 (1989).

Bolin, F. P.

Cheong, W. F.

W. F. Cheong, S. A. Prahl, A. J. Welch, “A review of the optical properties of biological tissues,” IEEE J. Quantum Electron. 26, 2166–2185 (1990).
[CrossRef]

Ference, R. J.

Gomer, C. J.

L. O. Svaasand, C. J. Gomer, “Optics of tissue,” in Dosimetry of Laser Radiation in Medicine and Biology, Proc. Soc. Photo-Opt. Instrum. Eng. IS-5, 114–132 (1989).

Prahl, S. A.

W. F. Cheong, S. A. Prahl, A. J. Welch, “A review of the optical properties of biological tissues,” IEEE J. Quantum Electron. 26, 2166–2185 (1990).
[CrossRef]

Preuss, L. E.

Svaasand, L. O.

L. O. Svaasand, C. J. Gomer, “Optics of tissue,” in Dosimetry of Laser Radiation in Medicine and Biology, Proc. Soc. Photo-Opt. Instrum. Eng. IS-5, 114–132 (1989).

Taylor, R. C.

Welch, A. J.

W. F. Cheong, S. A. Prahl, A. J. Welch, “A review of the optical properties of biological tissues,” IEEE J. Quantum Electron. 26, 2166–2185 (1990).
[CrossRef]

Wilson, B. C.

B. C. Wilson, “Modeling and measurements of light propagation in tissue for diagnostic and therapeutic applications,” in Laser Systems for Photobiology and Photomedicine, A. N. Chester, S. Martellucci, A. M. Scheggi, eds., Vol. 252 of NATO American Standards Institute Series (Plenum, New York, 1991), pp. 13–27.
[CrossRef]

Appl. Opt.

Dosimetry of Laser Radiation in Medicine and Biology

L. O. Svaasand, C. J. Gomer, “Optics of tissue,” in Dosimetry of Laser Radiation in Medicine and Biology, Proc. Soc. Photo-Opt. Instrum. Eng. IS-5, 114–132 (1989).

IEEE J. Quantum Electron.

W. F. Cheong, S. A. Prahl, A. J. Welch, “A review of the optical properties of biological tissues,” IEEE J. Quantum Electron. 26, 2166–2185 (1990).
[CrossRef]

Other

B. C. Wilson, “Modeling and measurements of light propagation in tissue for diagnostic and therapeutic applications,” in Laser Systems for Photobiology and Photomedicine, A. N. Chester, S. Martellucci, A. M. Scheggi, eds., Vol. 252 of NATO American Standards Institute Series (Plenum, New York, 1991), pp. 13–27.
[CrossRef]

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (2)

Fig. 1.
Fig. 1.

Specular reflectance versus incident angle.

Fig. 2.
Fig. 2.

Experimental setup for determining index of refraction: 1, sample; 2, semicylindrical lens; 3, photon detector; 4, He–Ne laser; 5, beam compressor; 6, plano–concave lens.

Tables (1)

Tables Icon

Table 1. Values of Indices of Some Tissues in vitro

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

n i × sin   θ c = n t    .
Δ n t = n t [ ( Δ N N ) 2 + ( cot  θΔθ ) 2 ] 1 / 2 .

Metrics