Abstract

We designed a quick and inexpensive system for spectral measurements of optical properties including absorption coefficient and reduced scattering coefficient. The system was based on oblique incidence reflectometry.[1] A broad band light source was coupled into an optic fiber to deliver light obliquely to turbid media. Nine detection optic fibers were used to collect the diffuse reflectance as a function of source-detector distance. The relative diffuse reflectance profile was used to deduce the absorption and reduced scattering spectra. The system was able to acquire data in a wavelength range of 256 nm within a fraction of a second.

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References

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  1. L.-H. Wang and S. L. Jacques, "Use of a laser beam with an oblique angle of incidence to measure the reduced scattering coefficient of a turbid medium," Appl. Opt. 34, 2362-2366 (1995).
    [CrossRef] [PubMed]
  2. S. L. Jacques, eds., Laser-Tissue Interaction VIII, Proc. SPIE 2975 (SPIE Press, Bellingham, WA, 1997).
  3. E. Sevick-Muraca and D. Benaron, eds., OSA Trends in Optics and Photonics on Biomedical Optical Spectroscopy and Diagnostics, vol. 3 (Optical Society of America, Washington, DC, 1996).
  4. B. Chance and R. R. Alfano, eds., Optical Tomography and Spectroscopy of Tissue: Theory, Instrumentation, Model, and Human Studies II, Proc. SPIE 2979 (SPIE Press, Bellingham, WA, 1997).
  5. S.-P. Lin, L.-H. Wang, S. L. Jacques and F. K. Tittel, "Measurement of tissue optical properties by the use of oblique-incidence optical fiber reflectometry," Appl. Opt. 36, 136-143 (1997).
    [CrossRef] [PubMed]
  6. S.-P. Lin, L.-H. Wang, S. L. Jacques, and F. K. Tittel, "Measurement of absorption and scattering spectra with oblique incidence reflectometry," in OSA Trends in Optics and Photonics on Biomedical Optical Spectroscopy and Diagnostics, E. Sevick-Muraca and D. Benaron, eds., vol. 3, 44-49 (Optical Society of America, Washington, D.C., 1996).
  7. G. Marquez, L.-H. Wang, S.-P. Lin, J. A. Schwartz, and S. L. Thomsen, "Anisotropy in the absorption and scattering spectra of chicken breast tissue," Appl. Opt., in press (1997).
  8. L.-H. Wang and S. L. Jacques, "Analysis of diffusion theory and similarity relations," Proc. SPIE 1888, 107-116 (1993).
    [CrossRef]
  9. T. J. Farrell, M. S. Patterson, and B. C. Wilson, "A diffusion theory model of spatially resolved, steady-state diffuse reflectance for the non-invasive determination of tissue optical properties in vivo," Med. Phys. 19, 879-888 (1992).
    [CrossRef] [PubMed]
  10. W. H. Press, B. P. Flannery, S. A. Teukolsky, and W. T. Veterlin, Numerical Recipes in C, 2nd ed. (Cambridge U. Press, Cambridge, UK, 1992), Section 15.5.

Other (10)

L.-H. Wang and S. L. Jacques, "Use of a laser beam with an oblique angle of incidence to measure the reduced scattering coefficient of a turbid medium," Appl. Opt. 34, 2362-2366 (1995).
[CrossRef] [PubMed]

S. L. Jacques, eds., Laser-Tissue Interaction VIII, Proc. SPIE 2975 (SPIE Press, Bellingham, WA, 1997).

E. Sevick-Muraca and D. Benaron, eds., OSA Trends in Optics and Photonics on Biomedical Optical Spectroscopy and Diagnostics, vol. 3 (Optical Society of America, Washington, DC, 1996).

B. Chance and R. R. Alfano, eds., Optical Tomography and Spectroscopy of Tissue: Theory, Instrumentation, Model, and Human Studies II, Proc. SPIE 2979 (SPIE Press, Bellingham, WA, 1997).

S.-P. Lin, L.-H. Wang, S. L. Jacques and F. K. Tittel, "Measurement of tissue optical properties by the use of oblique-incidence optical fiber reflectometry," Appl. Opt. 36, 136-143 (1997).
[CrossRef] [PubMed]

S.-P. Lin, L.-H. Wang, S. L. Jacques, and F. K. Tittel, "Measurement of absorption and scattering spectra with oblique incidence reflectometry," in OSA Trends in Optics and Photonics on Biomedical Optical Spectroscopy and Diagnostics, E. Sevick-Muraca and D. Benaron, eds., vol. 3, 44-49 (Optical Society of America, Washington, D.C., 1996).

G. Marquez, L.-H. Wang, S.-P. Lin, J. A. Schwartz, and S. L. Thomsen, "Anisotropy in the absorption and scattering spectra of chicken breast tissue," Appl. Opt., in press (1997).

L.-H. Wang and S. L. Jacques, "Analysis of diffusion theory and similarity relations," Proc. SPIE 1888, 107-116 (1993).
[CrossRef]

T. J. Farrell, M. S. Patterson, and B. C. Wilson, "A diffusion theory model of spatially resolved, steady-state diffuse reflectance for the non-invasive determination of tissue optical properties in vivo," Med. Phys. 19, 879-888 (1992).
[CrossRef] [PubMed]

W. H. Press, B. P. Flannery, S. A. Teukolsky, and W. T. Veterlin, Numerical Recipes in C, 2nd ed. (Cambridge U. Press, Cambridge, UK, 1992), Section 15.5.

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Figures (4)

Fig. 1.
Fig. 1.

Schematic of the experimental apparatus. White light was coupled to the oblique-incidence optical fiber probe. A source fiber delivered light to the phantom at an angle of 45° and the diffuse reflectance was collected by nine collection fibers. All fibers were encased to form a hand-held probe. The collected diffuse reflectance was dispersed by the spectrograph and then imaged onto the CCD matrix. The probe was moved to five different angles to perform five independent measurements.

Fig. 2.
Fig. 2.

Schematic representation of obliquely incident light. Note the shift in the center of diffuse reflectance, Δx . The position of the two point sources in diffusion theory model of oblique incidence reflectometry are shown.

Fig. 3.
Fig. 3.

The extracted optical properties of polystyrene spheres/trypan blue dye phantom before and after the wavelength alignment. (a) The absorption coefficient, μa , versus wavelength. (b) The reduced scattering coefficient, μs ', versus wavelength.

Fig. 4.
Fig. 4.

The average optical properties of polystyrene spheres/trypan blue dye phantom. (a) The absorption coefficient, μa , versus wavelength. (b) The reduced scattering coefficient, μs ', versus wavelength.

Equations (9)

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d s = 3 D = 1 0.35 μ a + μ s '
Δ x = sin ( α t ) 0.35 μ a + μ s '
R ( x ) = 1 4 [ Δ z ( 1 + μ eff ρ 1 ) exp ( μ eff ρ 1 ) ρ 1 3 + ( Δ z + 2 z b ) ( 1 + μ eff ρ 2 ) exp ( μ eff ρ 2 ) ρ 2 3 ]
z b = 2 A D
Δ z = cos ( α t ) 0.35 μ a + μ s ' = Δ x tan 1 ( α t )
μ eff = μ a D
D = Δ x 3 sin ( α t )
μ a = μ eff 2 Δ x 3 sin ( α t )
μ s ' = sin ( α t ) Δ x 0.35 μ a

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