Abstract

A prototype point-source integrating cavity absorption meter (PSICAM) is presented and compared with spectrophotometric absorption measurements. Different light collector assemblies of the PSICAM were tested regarding their capability to determine the absorption of water constituents accurately over a wide range of concentrations and scattering properties. The PSICAM setup with a radiance-type sensor showed the best performance. It was compared with a photometric absorption determination using nonscattering dye solutions. The mean difference between both methods was less than 2.4% in the spectral range of 400–700 nm. The absorption determination with the PSICAM, when equipped with a radiance sensor as a light collector, was only little affected by scattering and temperature. We conclude that the PSICAM can be used to determine the absorption of natural seawater samples at ambient temperatures.

© 2005 Optical Society of America

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References

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  1. W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
    [CrossRef]
  2. C. J.-Y. Lerebourg, D. A. Pilgrim, G. D. Ludbrook, R. Neal, “Development of a point source integrating cavity absorption meter,” J. Opt. 4, S56–S65 (2002).
  3. J. T. O. Kirk, Light and Photosynthesis in Aquatic Ecosystems, 2nd ed. (Cambridge U. Press, 1994).
    [CrossRef]
  4. S. Tassan, G. M. Ferrari, “An alternative approach to absorption measurements of aquatic particles retained on filters,” Limnol. Oceanogr. 40, 1358–1368 (1995).
    [CrossRef]
  5. C. S. Yentsch, “Measurements of visible light absorption by particulate matter in the ocean,” Limnol. Oceanogr. 7, 207–217 (1962).
    [CrossRef]
  6. J. T. O. Kirk, “Spectral absorption properties of natural waters: contribution of the soluble and particulate fractions to light absorption in some inland waters of southeastern Australia,” Aust. J. Mar. Freshwater Res. 31, 287–296 (1980).
    [CrossRef]
  7. H. Maske, H. Haardt, “Quantitative in vivo absorption spectra of phytoplankton: detrital absorption and comparison with fluorescence excitation spectra,” Limnol. Oceanogr. 32, 620–633 (1987).
    [CrossRef]
  8. M. Babin, D. Stramski, “Light absorption by aquatic particles in the near-infrared spectral region,” Limnol. Oceanogr. 47, 911–915 (2002).
    [CrossRef]
  9. C. S. Roesler, “Theoretical and experimental approaches to improve the accuracy of particulate absorption coefficients derived from quantitative filter technique,” Limnol. Oceanogr. 43, 1649–1660 (1998).
    [CrossRef]
  10. B. G. Mitchell, D. A. Kiefer, “Determination of absorption and fluorescence excitation spectra for phytoplankton,” in Marine Phytoplankton and Productivity, O. Holm-Hansen, ed. (Springer, 1984), pp. 157–169.
    [CrossRef]
  11. B. G. Mitchell, D. A. Kiefer, “Chlorophyll a specific absorption and fluorescence excitation spectra for light-limited phytoplankton,” Deep-Sea Res. 35, 639–663 (1988).
    [CrossRef]
  12. J. S. Cleveland, A. D. Weidemann, “Quantifying absorption by aquatic particles: a multiple scattering correction for glass-fiber filters,” Limnol. Oceanogr. 38, 1321–1327 (1993).
    [CrossRef]
  13. P. Elterman, “Integrating cavity spectroscopy,” Appl. Opt. 9, 2140–2142 (1970).
    [CrossRef] [PubMed]
  14. E. S. Fry, G. Kattawar, “Measurement of the absorption coefficient of ocean water using isotropic illumination,” Proc. SPIE 925, 142–148 (1988).
    [CrossRef]
  15. E. S. Fry, G. Kattawar, R. M. Pope, “Integrating cavity absorption meter,” Appl. Opt. 31, 2055–2065 (1992).
    [CrossRef] [PubMed]
  16. J. T. O. Kirk, “Modeling the performance of an integrating-cavity absorption meter: theory and calculations for a spherical cavity,” Appl. Opt. 34, 4397–4408 (1995).
    [CrossRef] [PubMed]
  17. J. T. O. Kirk, “Point-source integrating-cavity absorption meter: theoretical principles and numerical modeling,” Appl. Opt. 36, 6123–6128 (1997).
    [CrossRef] [PubMed]
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    [CrossRef]
  19. J. T. O. Kirk, Kirk Marine Optics, Murrumbateman, Australia (personal communication, 1999).
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    [CrossRef]
  21. B. R. Marshall, R. C. Smith, “Raman scattering and in-water ocean optical properties,” Appl. Opt. 29, 71–84 (1990).
    [CrossRef] [PubMed]
  22. C. D. Mobley, Light and Water. Radiative Transfer in Natural Waters (Academic, 1994).
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  24. H. Buiteveld, J. M. H. Hakvoort, M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).
    [CrossRef]
  25. W. S. Pegau, D. Gray, J. R. V. Zaneveld, “Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity,” Appl. Opt. 36, 6035–6046 (1997).
    [CrossRef] [PubMed]
  26. I. Trabjerg, N. K. Højerslev, “Temperature influence on light absorption by fresh water and seawater in the visible and near-infrared spectrum,” Appl. Opt. 35, 2653–2658 (1996).
    [CrossRef] [PubMed]
  27. R. Röttgers, personal observation.

2002 (2)

C. J.-Y. Lerebourg, D. A. Pilgrim, G. D. Ludbrook, R. Neal, “Development of a point source integrating cavity absorption meter,” J. Opt. 4, S56–S65 (2002).

M. Babin, D. Stramski, “Light absorption by aquatic particles in the near-infrared spectral region,” Limnol. Oceanogr. 47, 911–915 (2002).
[CrossRef]

2000 (1)

1998 (1)

C. S. Roesler, “Theoretical and experimental approaches to improve the accuracy of particulate absorption coefficients derived from quantitative filter technique,” Limnol. Oceanogr. 43, 1649–1660 (1998).
[CrossRef]

1997 (3)

1996 (1)

1995 (3)

J. T. O. Kirk, “Modeling the performance of an integrating-cavity absorption meter: theory and calculations for a spherical cavity,” Appl. Opt. 34, 4397–4408 (1995).
[CrossRef] [PubMed]

S. Tassan, G. M. Ferrari, “An alternative approach to absorption measurements of aquatic particles retained on filters,” Limnol. Oceanogr. 40, 1358–1368 (1995).
[CrossRef]

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

1994 (1)

H. Buiteveld, J. M. H. Hakvoort, M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).
[CrossRef]

1993 (1)

J. S. Cleveland, A. D. Weidemann, “Quantifying absorption by aquatic particles: a multiple scattering correction for glass-fiber filters,” Limnol. Oceanogr. 38, 1321–1327 (1993).
[CrossRef]

1992 (1)

1990 (1)

1988 (2)

E. S. Fry, G. Kattawar, “Measurement of the absorption coefficient of ocean water using isotropic illumination,” Proc. SPIE 925, 142–148 (1988).
[CrossRef]

B. G. Mitchell, D. A. Kiefer, “Chlorophyll a specific absorption and fluorescence excitation spectra for light-limited phytoplankton,” Deep-Sea Res. 35, 639–663 (1988).
[CrossRef]

1987 (1)

H. Maske, H. Haardt, “Quantitative in vivo absorption spectra of phytoplankton: detrital absorption and comparison with fluorescence excitation spectra,” Limnol. Oceanogr. 32, 620–633 (1987).
[CrossRef]

1980 (1)

J. T. O. Kirk, “Spectral absorption properties of natural waters: contribution of the soluble and particulate fractions to light absorption in some inland waters of southeastern Australia,” Aust. J. Mar. Freshwater Res. 31, 287–296 (1980).
[CrossRef]

1970 (1)

1962 (1)

C. S. Yentsch, “Measurements of visible light absorption by particulate matter in the ocean,” Limnol. Oceanogr. 7, 207–217 (1962).
[CrossRef]

Babin, M.

M. Babin, D. Stramski, “Light absorption by aquatic particles in the near-infrared spectral region,” Limnol. Oceanogr. 47, 911–915 (2002).
[CrossRef]

Buiteveld, H.

H. Buiteveld, J. M. H. Hakvoort, M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).
[CrossRef]

Cleveland, J. S.

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

J. S. Cleveland, A. D. Weidemann, “Quantifying absorption by aquatic particles: a multiple scattering correction for glass-fiber filters,” Limnol. Oceanogr. 38, 1321–1327 (1993).
[CrossRef]

Davis, C. O.

Donze, M.

H. Buiteveld, J. M. H. Hakvoort, M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).
[CrossRef]

Doss, W.

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

Downes, T. V.

Elterman, P.

Ferrari, G. M.

S. Tassan, G. M. Ferrari, “An alternative approach to absorption measurements of aquatic particles retained on filters,” Limnol. Oceanogr. 40, 1358–1368 (1995).
[CrossRef]

Fry, E. S.

Gray, D.

Haardt, H.

H. Maske, H. Haardt, “Quantitative in vivo absorption spectra of phytoplankton: detrital absorption and comparison with fluorescence excitation spectra,” Limnol. Oceanogr. 32, 620–633 (1987).
[CrossRef]

Hakvoort, J. M. H.

H. Buiteveld, J. M. H. Hakvoort, M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).
[CrossRef]

Højerslev, N. K.

Kattawar, G.

E. S. Fry, G. Kattawar, R. M. Pope, “Integrating cavity absorption meter,” Appl. Opt. 31, 2055–2065 (1992).
[CrossRef] [PubMed]

E. S. Fry, G. Kattawar, “Measurement of the absorption coefficient of ocean water using isotropic illumination,” Proc. SPIE 925, 142–148 (1988).
[CrossRef]

Kennedy, C. D.

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

Kiefer, D. A.

B. G. Mitchell, D. A. Kiefer, “Chlorophyll a specific absorption and fluorescence excitation spectra for light-limited phytoplankton,” Deep-Sea Res. 35, 639–663 (1988).
[CrossRef]

B. G. Mitchell, D. A. Kiefer, “Determination of absorption and fluorescence excitation spectra for phytoplankton,” in Marine Phytoplankton and Productivity, O. Holm-Hansen, ed. (Springer, 1984), pp. 157–169.
[CrossRef]

Kirk, J. T. O.

J. T. O. Kirk, “Point-source integrating-cavity absorption meter: theoretical principles and numerical modeling,” Appl. Opt. 36, 6123–6128 (1997).
[CrossRef] [PubMed]

J. T. O. Kirk, “Modeling the performance of an integrating-cavity absorption meter: theory and calculations for a spherical cavity,” Appl. Opt. 34, 4397–4408 (1995).
[CrossRef] [PubMed]

J. T. O. Kirk, “Spectral absorption properties of natural waters: contribution of the soluble and particulate fractions to light absorption in some inland waters of southeastern Australia,” Aust. J. Mar. Freshwater Res. 31, 287–296 (1980).
[CrossRef]

J. T. O. Kirk, Light and Photosynthesis in Aquatic Ecosystems, 2nd ed. (Cambridge U. Press, 1994).
[CrossRef]

J. T. O. Kirk, Kirk Marine Optics, Murrumbateman, Australia (personal communication, 1999).

Leathers, R. A.

Lerebourg, C. J.-Y.

C. J.-Y. Lerebourg, D. A. Pilgrim, G. D. Ludbrook, R. Neal, “Development of a point source integrating cavity absorption meter,” J. Opt. 4, S56–S65 (2002).

Ludbrook, G. D.

C. J.-Y. Lerebourg, D. A. Pilgrim, G. D. Ludbrook, R. Neal, “Development of a point source integrating cavity absorption meter,” J. Opt. 4, S56–S65 (2002).

Maffione, R. A.

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

Marshall, B. R.

Maske, H.

H. Maske, H. Haardt, “Quantitative in vivo absorption spectra of phytoplankton: detrital absorption and comparison with fluorescence excitation spectra,” Limnol. Oceanogr. 32, 620–633 (1987).
[CrossRef]

Mitchell, B. G.

B. G. Mitchell, D. A. Kiefer, “Chlorophyll a specific absorption and fluorescence excitation spectra for light-limited phytoplankton,” Deep-Sea Res. 35, 639–663 (1988).
[CrossRef]

B. G. Mitchell, D. A. Kiefer, “Determination of absorption and fluorescence excitation spectra for phytoplankton,” in Marine Phytoplankton and Productivity, O. Holm-Hansen, ed. (Springer, 1984), pp. 157–169.
[CrossRef]

Mobley, C. D.

C. D. Mobley, Light and Water. Radiative Transfer in Natural Waters (Academic, 1994).

Mueller, J. L.

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

Neal, R.

C. J.-Y. Lerebourg, D. A. Pilgrim, G. D. Ludbrook, R. Neal, “Development of a point source integrating cavity absorption meter,” J. Opt. 4, S56–S65 (2002).

Pegau, W. S.

W. S. Pegau, D. Gray, J. R. V. Zaneveld, “Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity,” Appl. Opt. 36, 6035–6046 (1997).
[CrossRef] [PubMed]

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

Pilgrim, D. A.

C. J.-Y. Lerebourg, D. A. Pilgrim, G. D. Ludbrook, R. Neal, “Development of a point source integrating cavity absorption meter,” J. Opt. 4, S56–S65 (2002).

Pope, R. M.

Roesler, C. S.

C. S. Roesler, “Theoretical and experimental approaches to improve the accuracy of particulate absorption coefficients derived from quantitative filter technique,” Limnol. Oceanogr. 43, 1649–1660 (1998).
[CrossRef]

Röttgers, R.

R. Röttgers, personal observation.

Smith, R. C.

Stone, R.

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

Stramski, D.

M. Babin, D. Stramski, “Light absorption by aquatic particles in the near-infrared spectral region,” Limnol. Oceanogr. 47, 911–915 (2002).
[CrossRef]

Tassan, S.

S. Tassan, G. M. Ferrari, “An alternative approach to absorption measurements of aquatic particles retained on filters,” Limnol. Oceanogr. 40, 1358–1368 (1995).
[CrossRef]

Trabjerg, I.

Trees, C. C.

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

Weidemann, A. D.

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

J. S. Cleveland, A. D. Weidemann, “Quantifying absorption by aquatic particles: a multiple scattering correction for glass-fiber filters,” Limnol. Oceanogr. 38, 1321–1327 (1993).
[CrossRef]

Wells, W. H.

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

Yentsch, C. S.

C. S. Yentsch, “Measurements of visible light absorption by particulate matter in the ocean,” Limnol. Oceanogr. 7, 207–217 (1962).
[CrossRef]

Zaneveld, J. R. V.

W. S. Pegau, D. Gray, J. R. V. Zaneveld, “Absorption and attenuation of visible and near-infrared light in water: dependence on temperature and salinity,” Appl. Opt. 36, 6035–6046 (1997).
[CrossRef] [PubMed]

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

Appl. Opt. (9)

Aust. J. Mar. Freshwater Res. (1)

J. T. O. Kirk, “Spectral absorption properties of natural waters: contribution of the soluble and particulate fractions to light absorption in some inland waters of southeastern Australia,” Aust. J. Mar. Freshwater Res. 31, 287–296 (1980).
[CrossRef]

Deep-Sea Res. (1)

B. G. Mitchell, D. A. Kiefer, “Chlorophyll a specific absorption and fluorescence excitation spectra for light-limited phytoplankton,” Deep-Sea Res. 35, 639–663 (1988).
[CrossRef]

J. Geophys. Res. (1)

W. S. Pegau, J. S. Cleveland, W. Doss, C. D. Kennedy, R. A. Maffione, J. L. Mueller, R. Stone, C. C. Trees, A. D. Weidemann, W. H. Wells, J. R. V. Zaneveld, “A comparison of methods for the measurements of the absorption coefficient in natural waters,” J. Geophys. Res. 100, 13201–13220 (1995).
[CrossRef]

J. Opt. (1)

C. J.-Y. Lerebourg, D. A. Pilgrim, G. D. Ludbrook, R. Neal, “Development of a point source integrating cavity absorption meter,” J. Opt. 4, S56–S65 (2002).

Limnol. Oceanogr. (6)

S. Tassan, G. M. Ferrari, “An alternative approach to absorption measurements of aquatic particles retained on filters,” Limnol. Oceanogr. 40, 1358–1368 (1995).
[CrossRef]

C. S. Yentsch, “Measurements of visible light absorption by particulate matter in the ocean,” Limnol. Oceanogr. 7, 207–217 (1962).
[CrossRef]

H. Maske, H. Haardt, “Quantitative in vivo absorption spectra of phytoplankton: detrital absorption and comparison with fluorescence excitation spectra,” Limnol. Oceanogr. 32, 620–633 (1987).
[CrossRef]

M. Babin, D. Stramski, “Light absorption by aquatic particles in the near-infrared spectral region,” Limnol. Oceanogr. 47, 911–915 (2002).
[CrossRef]

C. S. Roesler, “Theoretical and experimental approaches to improve the accuracy of particulate absorption coefficients derived from quantitative filter technique,” Limnol. Oceanogr. 43, 1649–1660 (1998).
[CrossRef]

J. S. Cleveland, A. D. Weidemann, “Quantifying absorption by aquatic particles: a multiple scattering correction for glass-fiber filters,” Limnol. Oceanogr. 38, 1321–1327 (1993).
[CrossRef]

Proc. SPIE (2)

E. S. Fry, G. Kattawar, “Measurement of the absorption coefficient of ocean water using isotropic illumination,” Proc. SPIE 925, 142–148 (1988).
[CrossRef]

H. Buiteveld, J. M. H. Hakvoort, M. Donze, “The optical properties of pure water,” Proc. SPIE 2258, 174–183 (1994).
[CrossRef]

Other (6)

R. Röttgers, personal observation.

C. D. Mobley, Light and Water. Radiative Transfer in Natural Waters (Academic, 1994).

R. M. Pope, “Optical absorption of pure water and seawater using the integrating cavity absorption meter,” Ph.D. dissertation (Texas A&M University, College Station, Texas, 1993).

J. T. O. Kirk, Kirk Marine Optics, Murrumbateman, Australia (personal communication, 1999).

B. G. Mitchell, D. A. Kiefer, “Determination of absorption and fluorescence excitation spectra for phytoplankton,” in Marine Phytoplankton and Productivity, O. Holm-Hansen, ed. (Springer, 1984), pp. 157–169.
[CrossRef]

J. T. O. Kirk, Light and Photosynthesis in Aquatic Ecosystems, 2nd ed. (Cambridge U. Press, 1994).
[CrossRef]

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Figures (11)

Fig. 1
Fig. 1

Cross sections of the PSICAM prototype with different collector assemblies. (a) Irradiance-type light collector with or without a baffle as used in setup I and IS, respectively. (b) Radiance-type collector of setup R.

Fig. 2
Fig. 2

Normalized spectral response of the light source and the detector measured in the PSICAM filled with purified water.

Fig. 3
Fig. 3

Normalized deviation of the halogen light source measured with the spectroradiometer for different wavelengths over a period of 5 h. The lamp and the radiometer were switched on 1 h before the start of this experiment.

Fig. 4
Fig. 4

Mean transmission (thick curve) and standard deviation (thin curves) determined from ten separate transmission measurements of water versus water with the radiance-type detector setup R.

Fig. 5
Fig. 5

Spectral absorption coefficient a (m−1) of four nigrosine solutions of different concentration as used to determine the effective wall reflectivity ρ.

Fig. 6
Fig. 6

Photometric measurements of BaSO4 suspensions of different concentrations. (a) Spectral scattering coefficient b (m−1). (b) Spectral transmission measured in front of an integrating sphere.

Fig. 7
Fig. 7

Spectral transmission of the BaSO4 suspensions measured with the different PSICAM setups: (a) Irradiance setup I, (b) irradiance plus baffle setup IS, (c) radiance setup R. The corresponding scattering coefficients b (m−1) are shown in Fig. 6.

Fig. 8
Fig. 8

Spectral reflectivity ρ determined with four different nigrosine solutions using the three different PSICAM setups: (a) Irradiance setup I, (b) irradiance plus baffle setup IS, (c) radiance setup R. The approximate spectral absorption of each solution is shown in Fig. 5.

Fig. 9
Fig. 9

(a) Different estimates for the spectral temperature coefficient ΨT of the absorption of pure water. The spectral data of Buiteveld et al.24 minus an offset (shown in parentheses) were used to calculate absorption of water at different temperatures. An additional modeled spectrum is shown.25 (b) Spectral reflectivity ρ determined at different temperatures. Spectra at 5 °C are shown for the calculation of pure water absorption with a different offset for ΨT (see above).

Fig. 10
Fig. 10

Spectral absorption coefficients a (m−1) of humic acid solutions of four different concentrations determined with the photometer (dotted curves) and the PSICAM (solid curves). (a) Linear scale. (b) Semilogarithmic scale.

Fig. 11
Fig. 11

Spectral absorption coefficients a (m−1) of a CuSO4 solution determined with the photometer (dotted curves) and the PSICAM (solid curves). (a) Linear scale. (b) semilogarithmic scale.

Tables (1)

Tables Icon

Table 1 Relative Differences in Absorption Determined with the PSICAM to that Determined with the Photometera

Equations (12)

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

T A B = F 0 A F 0 B = N C A N C B .
N C = P 0 + P 0 ρ P s + P 0 ρ 2 P s 2 + = P 0 n = 0 ( ρ P s ) n = P 0 / ( 1 - ρ P s ) .
T A B = P 0 A ( 1 - ρ P s B ) P 0 B ( 1 - ρ P s A ) .
P 0 ( a , r 0 ) = exp ( - a r 0 ) ,
P s ( a , r ) = 1 2 a 2 r 2 [ 1 - exp ( - 2 a r ) ( 2 a r + 1 ) ] .
T A B = exp [ - r 0 ( a A - a B ) ] [ 1 - ρ P s ( a B , r ) 1 - ρ P s ( a A , r ) ] .
N C = P 0 ρ P s + P s ρ 2 P s 2 + = P 0 n = 1 ( ρ P s ) n = ρ P 0 P s 1 - ρ P s .
T A B = P 0 A ( 1 - ρ P s B ) P 0 B ( 1 - ρ P s A ) P s A P s B = exp [ - r 0 ( a A - a B ) ] [ 1 - ρ P s ( a B , r ) 1 - ρ P s ( a A , r ) P s ( a A , r ) P s ( a B , r ) ] .
ρ = T A B exp ( - a B r 0 ) - exp ( - a A r 0 ) T A B exp ( - a B r 0 ) P s ( a A , r ) - exp ( - a A r 0 ) P s ( a B , r ) ,
ρ = T A B exp ( - a B r 0 ) P s ( a B , r ) - exp ( - a A r 0 ) P 0 ( a A , r ) T A B exp ( - a B r 0 ) P s ( a A , r ) P s ( a B , r ) - exp ( - a A r 0 ) P s ( a B , r ) P s ( a B , r ) .
G [ a ( λ ) ] = [ T num ( λ ) - T exp ( λ ) ] 2 ,
a T ( λ ) = a 20 ° C ( λ ) + ( T - 20 ) Ψ T .

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