OSA's Digital Library

Applied Optics

Applied Optics


  • Vol. 6, Iss. 1 — Jan. 1, 1967
  • pp: 119–124

Approximate Normal Emissivity Spectra in the Infrared at Elevated Temperatures of Single-Crystal and Polycrystalline Calcium Fluoride

W. Fussell and J. Geist  »View Author Affiliations

Applied Optics, Vol. 6, Issue 1, pp. 119-124 (1967)

View Full Text Article

Enhanced HTML    Acrobat PDF (711 KB)

Browse Journals / Lookup Meetings

Browse by Journal and Year


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools



A single-beam ir spectroradiometric system has been used to measure the normal spectral emissivity of specimens of single-crystal and polycrystalline calcium fluoride in the ir at elevated temperatures. The wavelength range was 2–12 μ, and data were taken at sample temperatures of 500°C and 600°C. Room temperature data on the index of refraction of single-crystal calcium fluoride and its rate of change with temperature were extrapolated to 500°C and 600°C; the normal spectral reflectivities were computed from the extrapolated indices at these temperatures. Then the computed reflectivities were used to extract normal spectral absorption coefficients from the emissivity data. It was possible to compute absorption coefficients with reasonable accuracy at wavelengths of 6 μ, 8 μ, and 10 μ; the smallest estimated error was about 2% at 8 μ. The absorption coefficients increased markedly with temperature at these three wavelengths. The absorption coefficients of the polycrystalline material were consistently higher than the corresponding values for the single-crystal calcium fluoride. It was found that the spectral absorption coefficients at 8 μ and 10 μ microns varied approximately as the 2.1 and 1.6 power of the absolute temperature, respectively, between room temperature and 600°C. These exponents lie within the range predicted by theory.

© 1967 Optical Society of America

Original Manuscript: August 25, 1966
Published: January 1, 1967

W. Fussell and J. Geist, "Approximate Normal Emissivity Spectra in the Infrared at Elevated Temperatures of Single-Crystal and Polycrystalline Calcium Fluoride," Appl. Opt. 6, 119-124 (1967)

Sort:  Author  |  Year  |  Journal  |  Reset  


  1. I. H. Malitson, Appl. Opt. 2, 1103 (1963). [CrossRef]
  2. D. E. Gray, Ed., American Institute of Physics; Handbook (McGraw-Hill Book Co., New York, 1963), 2nd ed., Chap. 6, p. 53.
  3. H. O. McMahon, J. Opt. Soc. Am. 40, 376 (1950). [CrossRef]
  4. Reference 2, Chap. 6, p. 103.
  5. D. V. Widder, Advanced Calculus (Prentice–Hall, Inc., New York, 1947), Chap. 1, p. 47
  6. R. H. Hamilton, Ind. and Eng. Chem. (Anal. Ed.) 16, 123 (1944).
  7. M. Born, K. Huang, Dynamical Theory of Crystal Lattices (Oxford University Press, London, 1954), Chap. 7, pp. 357–361.

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.


Fig. 1 Fig. 2 Fig. 3
Fig. 4

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited