Abstract

The reflection properties of pressed polytetrafluoroethylene powder have been under investigation by the Radiometric Physics Division at the National Bureau of Standards for the past five years. This material has a great potential use, both as a standard of diffuse reflectance and as a coating for integrating spheres for applications in reflectance spectrophotometry and other signal-averaging devices. It possesses certain physical and optical properties that make it ideal for use in these applications. Techniques are given for preparing reflection standards and coating integrating spheres with the pressed powder. The effects of powder density and thickness on its reflectance are reported, and observations of possible problems with fluorescence that are due to the presence of contaminants in the powder are discussed. The absolute reflectance (6°/hemispherical reflectance factor relative to a perfect diffuser) is reported for the spectral range of 200–2500 nm. The directional/hemispherical reflectance factor relative to 6°/hemispherical reflectance is given for several wavelengths in the ultraviolet and visible spectrum and for angles of incidence between 5 and 75°. The bidirectional reflectance factor is reported for 300, 600, and 1500 nm at angles of incidence of −10, −30, −50, and −70° and at viewing angles at 10° intervals from −80 to +80°.

© 1981 Optical Society of America

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References

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  1. The polytetrafluoroethylene powder used in these investigations is manufactured by Allied Chemical Company. The material is commonly referred to by the trade name Halon and is further identified as type G-80 tetrafluoroethylene resin. The commercial name of this material is given here for purposes of identification only and in no way implies endorsement by the National Bureau of Standards.
  2. Bureau Central de la Commission Internationale de l’Eclairage, Review of Publications on Properties and Reflection Values of Material Reflection Standards (Paris, 1979), CIE Publication 46 (TC-2.3), pp. 15–72.
  3. The term “perfect diffuser” is defined in Bureau Central de la Commission Internationale de l’Eclairage, International Lighting Vocabulary (Paris, 1970), CIE Publication 17 (E-1.1), p. 95.
  4. F. Grum and M. Saltzman, P-75-77 New White Standard of Reflectance (Paris, 1976), CIE Publication 36, 91.
  5. W. H. Venable, J. J. Hsia, and V. R. Weidner, “Development of an NBS reference spectrophotometer for diffuse reflectance and transmittance,” Nat. Bur. Stand. U.S. Tech. Note 594-11, 47 pp. (1976).
  6. V. R. Weidner and J. J. Hsia, “NBS specular reflectometer–spectrophotometer,” Appl. Opt. 19, 1268–1273 (1980).
    [Crossref] [PubMed]
  7. W. H. Venable, J. J. Hsia, and V. R. Weidner, “Establishing a scale of directional–hemispherical reflectance factor I: the Van den Akker method,” J. Res. Nat. Bur. Stand. 82, 29–55, (1977).
    [Crossref]
  8. E. I. Du Pont de Nemours and Company, Inc., Fluorocarbons Division, Teflon Fluorocarbon Resins—Safety in Handling and Use (Wilmington, Del., 1970), pp. 1–10. This publication references technical papers dealing with the thermal decomposition of fluorocarbons and associated safety problems.
  9. The following U.S. patents are assigned to J. A. Seiner of PPG Industries, Inc., Pittsburgh, Pa.: U.S. Patent No. 3,956,201, May11, 1976, and U.S. Patent No. 3,764,364, October9, 1973.
  10. From uncorrected emission spectra supplied by K. Mielenz and R. Velapoldi using the reference spectrofluorimeter in the NBS Center for Analytical Chemistry.
  11. R. D. Saunders and W. R. Ott, “Spectral irradiance measurements: effect of UV produced fluorescence in integrating spheres,” Appl. Opt. 15, 827–828 (1976).
    [Crossref] [PubMed]

1980 (1)

1977 (1)

W. H. Venable, J. J. Hsia, and V. R. Weidner, “Establishing a scale of directional–hemispherical reflectance factor I: the Van den Akker method,” J. Res. Nat. Bur. Stand. 82, 29–55, (1977).
[Crossref]

1976 (2)

R. D. Saunders and W. R. Ott, “Spectral irradiance measurements: effect of UV produced fluorescence in integrating spheres,” Appl. Opt. 15, 827–828 (1976).
[Crossref] [PubMed]

W. H. Venable, J. J. Hsia, and V. R. Weidner, “Development of an NBS reference spectrophotometer for diffuse reflectance and transmittance,” Nat. Bur. Stand. U.S. Tech. Note 594-11, 47 pp. (1976).

Grum, F.

F. Grum and M. Saltzman, P-75-77 New White Standard of Reflectance (Paris, 1976), CIE Publication 36, 91.

Hsia, J. J.

V. R. Weidner and J. J. Hsia, “NBS specular reflectometer–spectrophotometer,” Appl. Opt. 19, 1268–1273 (1980).
[Crossref] [PubMed]

W. H. Venable, J. J. Hsia, and V. R. Weidner, “Establishing a scale of directional–hemispherical reflectance factor I: the Van den Akker method,” J. Res. Nat. Bur. Stand. 82, 29–55, (1977).
[Crossref]

W. H. Venable, J. J. Hsia, and V. R. Weidner, “Development of an NBS reference spectrophotometer for diffuse reflectance and transmittance,” Nat. Bur. Stand. U.S. Tech. Note 594-11, 47 pp. (1976).

Ott, W. R.

Saltzman, M.

F. Grum and M. Saltzman, P-75-77 New White Standard of Reflectance (Paris, 1976), CIE Publication 36, 91.

Saunders, R. D.

Seiner, J. A.

The following U.S. patents are assigned to J. A. Seiner of PPG Industries, Inc., Pittsburgh, Pa.: U.S. Patent No. 3,956,201, May11, 1976, and U.S. Patent No. 3,764,364, October9, 1973.

Venable, W. H.

W. H. Venable, J. J. Hsia, and V. R. Weidner, “Establishing a scale of directional–hemispherical reflectance factor I: the Van den Akker method,” J. Res. Nat. Bur. Stand. 82, 29–55, (1977).
[Crossref]

W. H. Venable, J. J. Hsia, and V. R. Weidner, “Development of an NBS reference spectrophotometer for diffuse reflectance and transmittance,” Nat. Bur. Stand. U.S. Tech. Note 594-11, 47 pp. (1976).

Weidner, V. R.

V. R. Weidner and J. J. Hsia, “NBS specular reflectometer–spectrophotometer,” Appl. Opt. 19, 1268–1273 (1980).
[Crossref] [PubMed]

W. H. Venable, J. J. Hsia, and V. R. Weidner, “Establishing a scale of directional–hemispherical reflectance factor I: the Van den Akker method,” J. Res. Nat. Bur. Stand. 82, 29–55, (1977).
[Crossref]

W. H. Venable, J. J. Hsia, and V. R. Weidner, “Development of an NBS reference spectrophotometer for diffuse reflectance and transmittance,” Nat. Bur. Stand. U.S. Tech. Note 594-11, 47 pp. (1976).

Appl. Opt. (2)

J. Res. Nat. Bur. Stand. (1)

W. H. Venable, J. J. Hsia, and V. R. Weidner, “Establishing a scale of directional–hemispherical reflectance factor I: the Van den Akker method,” J. Res. Nat. Bur. Stand. 82, 29–55, (1977).
[Crossref]

Nat. Bur. Stand. U.S. Tech. Note (1)

W. H. Venable, J. J. Hsia, and V. R. Weidner, “Development of an NBS reference spectrophotometer for diffuse reflectance and transmittance,” Nat. Bur. Stand. U.S. Tech. Note 594-11, 47 pp. (1976).

Other (7)

E. I. Du Pont de Nemours and Company, Inc., Fluorocarbons Division, Teflon Fluorocarbon Resins—Safety in Handling and Use (Wilmington, Del., 1970), pp. 1–10. This publication references technical papers dealing with the thermal decomposition of fluorocarbons and associated safety problems.

The following U.S. patents are assigned to J. A. Seiner of PPG Industries, Inc., Pittsburgh, Pa.: U.S. Patent No. 3,956,201, May11, 1976, and U.S. Patent No. 3,764,364, October9, 1973.

From uncorrected emission spectra supplied by K. Mielenz and R. Velapoldi using the reference spectrofluorimeter in the NBS Center for Analytical Chemistry.

The polytetrafluoroethylene powder used in these investigations is manufactured by Allied Chemical Company. The material is commonly referred to by the trade name Halon and is further identified as type G-80 tetrafluoroethylene resin. The commercial name of this material is given here for purposes of identification only and in no way implies endorsement by the National Bureau of Standards.

Bureau Central de la Commission Internationale de l’Eclairage, Review of Publications on Properties and Reflection Values of Material Reflection Standards (Paris, 1979), CIE Publication 46 (TC-2.3), pp. 15–72.

The term “perfect diffuser” is defined in Bureau Central de la Commission Internationale de l’Eclairage, International Lighting Vocabulary (Paris, 1970), CIE Publication 17 (E-1.1), p. 95.

F. Grum and M. Saltzman, P-75-77 New White Standard of Reflectance (Paris, 1976), CIE Publication 36, 91.

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Figures (6)

Fig. 1
Fig. 1

The NBS integrating-sphere-coating apparatus showing the hemisphere manipulator with the electronically controlled tamping head used to press the PTFE powder into the hemisphere with a uniform radius.

Fig. 2
Fig. 2

Pressed PTFE powder reflectance as a function of powder density (10-mm thickness).

Fig. 3
Fig. 3

The 6°/hemispherical reflectance factor (relative to a perfect diffuser) of 10-mm-thick, 1-g/cm3-density pressed PTFE powder.

Fig. 4
Fig. 4

The directional/hemispherical reflectance factor of pressed PTFE powder as a function of angle of incidence and wavelength.

Fig. 5
Fig. 5

The bidirectional reflectance factor at 600 nm of pressed PTFE powder having a rough surface finish.

Fig. 6
Fig. 6

The bidirectional reflectance factor at 600 nm of pressed barium sulfate powder having a rough surface finish.

Tables (5)

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Table 1 Reflectance of Pressed PTFE Powder (0.8 g/cm3) Relative to That of a 10-mm-Thick Layer at Each Wavelength

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Table 2 Data from Fluorescence Check

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Table 3 6°/Hemispherical Reflectance Factor of a 10-mm-Thick Pressed PTFE Powder Relative to a Perfect Diffuser

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Table 4 Directional/Hemispherical Reflectance Factor of Pressed PTFE Powder for a 10-mm-Thick Coating (Relative to Hemispherical Reflectance at 6° Incidence)

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Table 5 Directional/Directional Reflectance Factor (Bidirectional Reflectance) of 10-mm-Thick Pressed PTFE Powder