Abstract

The effects of fiber coupling and fiber length on photocurrent fluctuations are studied when the light of a laser diode transmitted to and from a dynamic turbid medium by a step-index multimode fiber is studied. When the laser light is coupled asymmetrically, filling only the higher-order modes, the photocurrent fluctuations are suppressed significantly when fiber lengths of as much as 16 m are added between the laser and the medium. Addition of as much as 16 m of detection fiber, or any fiber in the case of symmetric light coupling, leads to much less or no suppression of the photocurrent fluctuations.

© 2004 Optical Society of America

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References

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  1. G. E. Nilsson, T. Tenland, P. Å. Öberg, “A new instrument for continuous measurement of tissue blood flow by light beating spectroscopy,” IEEE Trans. Biomed. Eng. 27, 12–18 (1980).
    [CrossRef]
  2. F. F. M. de Mul, M. H. Koelink, A. L. Weijers, J. Greve, J. G. Aarnoudse, R. Graaff, A. C. M. Dassel, “A semiconductor-laser used for direct measurement of the blood perfusion of tissue,” IEEE Trans. Biomed. Eng. 40, 208–210 (1993).
    [CrossRef] [PubMed]
  3. A. Jakobsson, G. E. Nilsson, “Prediction of sampling depth and photon pathlength in laser Doppler flowmetry,” Med. Biol. Eng. Comput. 31, 301–307 (1993).
    [CrossRef]
  4. W. Steenbergen, F. F. M. de Mul, “Role of speckles in laser Doppler flowmetry,” in Optical Diagnostics of Biological Fluids III, A. V. Priezzhev, T. Asakura, J. D. Briers, A. Katzir, eds., Proc. SPIE3252, 14–25 (1998).
    [CrossRef]
  5. R. J. Gush, T. A. King, “Discrimination of capillary and arterio-venular blood flow in skin by laser Doppler flowmetry,” Med. Biol. Eng. Comput. 29, 387–392 (1991).
    [CrossRef]
  6. J. Wilson, J. F. B. Hawkes, Optoelectronics: An Introduction (Prentice-Hall, New York, 1989).
  7. B. Crosignani, B. Diano, P. Di Porto, “Speckle-pattern visibility of light transmitted through a multimode optical fiber,” J. Opt. Soc. Am. 66, 1312–1313 (1976).
    [CrossRef]
  8. M. Imai, T. Asakura, “Speckle contrast of laser light transmitted through multimode optical fiber,” Optik (Stuttgart) 48, 335–340 (1977).
  9. H. Fujii, T. Asakura, “Blood flow observed by time-varying laser speckle,” Opt. Lett. 10, 104–106 (1985).
    [CrossRef] [PubMed]
  10. J. D. Briers, “Laser Doppler and time-varying speckle: a reconciliation,” J. Opt. Soc. Am. A 13, 345–350 (1996).
    [CrossRef]
  11. A. Serov, W. Steenbergen, F. de Mul, “Prediction of the photodetector signal generated by Doppler-induced speckle fluctuations: theory and some validations,” J. Opt. Soc. Am. A 18, 622–630 (2001).
    [CrossRef]

2001 (1)

1996 (1)

1993 (2)

F. F. M. de Mul, M. H. Koelink, A. L. Weijers, J. Greve, J. G. Aarnoudse, R. Graaff, A. C. M. Dassel, “A semiconductor-laser used for direct measurement of the blood perfusion of tissue,” IEEE Trans. Biomed. Eng. 40, 208–210 (1993).
[CrossRef] [PubMed]

A. Jakobsson, G. E. Nilsson, “Prediction of sampling depth and photon pathlength in laser Doppler flowmetry,” Med. Biol. Eng. Comput. 31, 301–307 (1993).
[CrossRef]

1991 (1)

R. J. Gush, T. A. King, “Discrimination of capillary and arterio-venular blood flow in skin by laser Doppler flowmetry,” Med. Biol. Eng. Comput. 29, 387–392 (1991).
[CrossRef]

1985 (1)

1980 (1)

G. E. Nilsson, T. Tenland, P. Å. Öberg, “A new instrument for continuous measurement of tissue blood flow by light beating spectroscopy,” IEEE Trans. Biomed. Eng. 27, 12–18 (1980).
[CrossRef]

1977 (1)

M. Imai, T. Asakura, “Speckle contrast of laser light transmitted through multimode optical fiber,” Optik (Stuttgart) 48, 335–340 (1977).

1976 (1)

Aarnoudse, J. G.

F. F. M. de Mul, M. H. Koelink, A. L. Weijers, J. Greve, J. G. Aarnoudse, R. Graaff, A. C. M. Dassel, “A semiconductor-laser used for direct measurement of the blood perfusion of tissue,” IEEE Trans. Biomed. Eng. 40, 208–210 (1993).
[CrossRef] [PubMed]

Asakura, T.

H. Fujii, T. Asakura, “Blood flow observed by time-varying laser speckle,” Opt. Lett. 10, 104–106 (1985).
[CrossRef] [PubMed]

M. Imai, T. Asakura, “Speckle contrast of laser light transmitted through multimode optical fiber,” Optik (Stuttgart) 48, 335–340 (1977).

Briers, J. D.

Crosignani, B.

Dassel, A. C. M.

F. F. M. de Mul, M. H. Koelink, A. L. Weijers, J. Greve, J. G. Aarnoudse, R. Graaff, A. C. M. Dassel, “A semiconductor-laser used for direct measurement of the blood perfusion of tissue,” IEEE Trans. Biomed. Eng. 40, 208–210 (1993).
[CrossRef] [PubMed]

de Mul, F.

de Mul, F. F. M.

F. F. M. de Mul, M. H. Koelink, A. L. Weijers, J. Greve, J. G. Aarnoudse, R. Graaff, A. C. M. Dassel, “A semiconductor-laser used for direct measurement of the blood perfusion of tissue,” IEEE Trans. Biomed. Eng. 40, 208–210 (1993).
[CrossRef] [PubMed]

W. Steenbergen, F. F. M. de Mul, “Role of speckles in laser Doppler flowmetry,” in Optical Diagnostics of Biological Fluids III, A. V. Priezzhev, T. Asakura, J. D. Briers, A. Katzir, eds., Proc. SPIE3252, 14–25 (1998).
[CrossRef]

Di Porto, P.

Diano, B.

Fujii, H.

Graaff, R.

F. F. M. de Mul, M. H. Koelink, A. L. Weijers, J. Greve, J. G. Aarnoudse, R. Graaff, A. C. M. Dassel, “A semiconductor-laser used for direct measurement of the blood perfusion of tissue,” IEEE Trans. Biomed. Eng. 40, 208–210 (1993).
[CrossRef] [PubMed]

Greve, J.

F. F. M. de Mul, M. H. Koelink, A. L. Weijers, J. Greve, J. G. Aarnoudse, R. Graaff, A. C. M. Dassel, “A semiconductor-laser used for direct measurement of the blood perfusion of tissue,” IEEE Trans. Biomed. Eng. 40, 208–210 (1993).
[CrossRef] [PubMed]

Gush, R. J.

R. J. Gush, T. A. King, “Discrimination of capillary and arterio-venular blood flow in skin by laser Doppler flowmetry,” Med. Biol. Eng. Comput. 29, 387–392 (1991).
[CrossRef]

Hawkes, J. F. B.

J. Wilson, J. F. B. Hawkes, Optoelectronics: An Introduction (Prentice-Hall, New York, 1989).

Imai, M.

M. Imai, T. Asakura, “Speckle contrast of laser light transmitted through multimode optical fiber,” Optik (Stuttgart) 48, 335–340 (1977).

Jakobsson, A.

A. Jakobsson, G. E. Nilsson, “Prediction of sampling depth and photon pathlength in laser Doppler flowmetry,” Med. Biol. Eng. Comput. 31, 301–307 (1993).
[CrossRef]

King, T. A.

R. J. Gush, T. A. King, “Discrimination of capillary and arterio-venular blood flow in skin by laser Doppler flowmetry,” Med. Biol. Eng. Comput. 29, 387–392 (1991).
[CrossRef]

Koelink, M. H.

F. F. M. de Mul, M. H. Koelink, A. L. Weijers, J. Greve, J. G. Aarnoudse, R. Graaff, A. C. M. Dassel, “A semiconductor-laser used for direct measurement of the blood perfusion of tissue,” IEEE Trans. Biomed. Eng. 40, 208–210 (1993).
[CrossRef] [PubMed]

Nilsson, G. E.

A. Jakobsson, G. E. Nilsson, “Prediction of sampling depth and photon pathlength in laser Doppler flowmetry,” Med. Biol. Eng. Comput. 31, 301–307 (1993).
[CrossRef]

G. E. Nilsson, T. Tenland, P. Å. Öberg, “A new instrument for continuous measurement of tissue blood flow by light beating spectroscopy,” IEEE Trans. Biomed. Eng. 27, 12–18 (1980).
[CrossRef]

Öberg, P. Å.

G. E. Nilsson, T. Tenland, P. Å. Öberg, “A new instrument for continuous measurement of tissue blood flow by light beating spectroscopy,” IEEE Trans. Biomed. Eng. 27, 12–18 (1980).
[CrossRef]

Serov, A.

Steenbergen, W.

A. Serov, W. Steenbergen, F. de Mul, “Prediction of the photodetector signal generated by Doppler-induced speckle fluctuations: theory and some validations,” J. Opt. Soc. Am. A 18, 622–630 (2001).
[CrossRef]

W. Steenbergen, F. F. M. de Mul, “Role of speckles in laser Doppler flowmetry,” in Optical Diagnostics of Biological Fluids III, A. V. Priezzhev, T. Asakura, J. D. Briers, A. Katzir, eds., Proc. SPIE3252, 14–25 (1998).
[CrossRef]

Tenland, T.

G. E. Nilsson, T. Tenland, P. Å. Öberg, “A new instrument for continuous measurement of tissue blood flow by light beating spectroscopy,” IEEE Trans. Biomed. Eng. 27, 12–18 (1980).
[CrossRef]

Weijers, A. L.

F. F. M. de Mul, M. H. Koelink, A. L. Weijers, J. Greve, J. G. Aarnoudse, R. Graaff, A. C. M. Dassel, “A semiconductor-laser used for direct measurement of the blood perfusion of tissue,” IEEE Trans. Biomed. Eng. 40, 208–210 (1993).
[CrossRef] [PubMed]

Wilson, J.

J. Wilson, J. F. B. Hawkes, Optoelectronics: An Introduction (Prentice-Hall, New York, 1989).

IEEE Trans. Biomed. Eng. (2)

G. E. Nilsson, T. Tenland, P. Å. Öberg, “A new instrument for continuous measurement of tissue blood flow by light beating spectroscopy,” IEEE Trans. Biomed. Eng. 27, 12–18 (1980).
[CrossRef]

F. F. M. de Mul, M. H. Koelink, A. L. Weijers, J. Greve, J. G. Aarnoudse, R. Graaff, A. C. M. Dassel, “A semiconductor-laser used for direct measurement of the blood perfusion of tissue,” IEEE Trans. Biomed. Eng. 40, 208–210 (1993).
[CrossRef] [PubMed]

J. Opt. Soc. Am. (1)

J. Opt. Soc. Am. A (2)

Med. Biol. Eng. Comput. (2)

A. Jakobsson, G. E. Nilsson, “Prediction of sampling depth and photon pathlength in laser Doppler flowmetry,” Med. Biol. Eng. Comput. 31, 301–307 (1993).
[CrossRef]

R. J. Gush, T. A. King, “Discrimination of capillary and arterio-venular blood flow in skin by laser Doppler flowmetry,” Med. Biol. Eng. Comput. 29, 387–392 (1991).
[CrossRef]

Opt. Lett. (1)

Optik (Stuttgart) (1)

M. Imai, T. Asakura, “Speckle contrast of laser light transmitted through multimode optical fiber,” Optik (Stuttgart) 48, 335–340 (1977).

Other (2)

J. Wilson, J. F. B. Hawkes, Optoelectronics: An Introduction (Prentice-Hall, New York, 1989).

W. Steenbergen, F. F. M. de Mul, “Role of speckles in laser Doppler flowmetry,” in Optical Diagnostics of Biological Fluids III, A. V. Priezzhev, T. Asakura, J. D. Briers, A. Katzir, eds., Proc. SPIE3252, 14–25 (1998).
[CrossRef]

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Figures (7)

Fig. 1
Fig. 1

Sketch of the setup that we used to study the effects of the length of connecting fibers. Additional fibers of various lengths were inserted either between the laser and the probe at point A or between the probe and the detector at point B. Inset, photo of two LDPM probes used in this study.

Fig. 2
Fig. 2

Speckle pattern taken with the 250-μm probe after the illumination fiber (a) without elongating fibers and (b) with an additional 16-m-long elongating fiber. The well-defined ring structure in (a) indicates that mostly the highest fiber modes are excited, and in (b) part of the optical power is coupled into lower orders as a result of intermodal mixing.

Fig. 3
Fig. 3

(a) Optical power spectra and (b) the corresponding autocorrelation function calculated as a Fourier transform of the spectrum for the laser diodes of the PF5000 LDPM device and the MoorLab LDPM device.

Fig. 4
Fig. 4

Variation of the flux readings of the PF5000 monitor as a function of the length of additional fiber (a) added to the illumination fiber between the laser source and the 250-μm probe and (b) added to the detector fiber between the probe and the detector. Results obtained with three laser configurations are shown. The vertical axis at the left gives results in perfusion units of the monitor; the right-hand axis is the corresponding output voltage. The dashed horizontal line at 250 P.U. shows the calibration level; the solid line is a linear fit to the data obtained with the asymmetrically coupled diode laser.

Fig. 5
Fig. 5

Similar to Fig. 4 but measured with the 500-μm probe.

Fig. 6
Fig. 6

Variation of (a) the flux and (b) the concentration reading of the MoorLab monitor as a function of the length of an additional fiber inserted between the laser and the probe. CU, concentration units.

Fig. 7
Fig. 7

Reduction of flux signal and squared speckle contrast as functions of the additional length of the illumination fiber for the asymmetric diode laser. A particle suspension was used for flux measurements, whereas the speckle contrast was measured with a statically scattering object as the medium.

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Δl=LNA2/2n1,

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