A study of the reflection factor of usual photometric standards in the near infra-red

Abstract

The spectral reflectance of various samples of pressed powders of MgO and BaSO₄ were determined in the near infra-red (up to 2. 5 μm). The paper describes two semi-absolute methods used, the results yielded being converted into absolute values by extending the measurements in the visible region where the behaviour of the samples was well known. Above 1.1 μm the results show that different samples which remain substantially comparable in the visible, begin to depart significantly from each other depending on the origin of the powder. The study of MgO also illustrated the strong influence of moisture or even of the duration of rest in a normal laboratory atmosphere, whereas BaSO₄ is largely free from such defects. MgO samples were therefore discarded. The paper reports the studies carried out on samples of BaSO₄ from the different sources.

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References

Blevin, W.R. , and Brown, W.J. , An infra-red reflectometer with a spherical mirror, in Journal of Scientific Instruments, no. 42, 385 (1965).

White, J.U. , New method for measuring diffuse reflectance in the infra-red, JOSA, 54, 1332 (1964).

Edwards, O.K. , Gier, J.T. , Nelson, K.E. , and Roddick, R.D. , Integrating sphere for imperfectly diffuse samples, JOSA, 51, 1279 (1961).

Tellex, P.A. , and Waldron, J.P. , Reflectance of magnesium oxide, JOSA, 45, 19 (1955).

Middleton, W.E.K. , and Sanders, L.L. , The absolute spectral diffuse reflectance of magnesium oxide, JOSA, no. 41, 419 (1951).

Korte, H. , and Schmidt, M. , Uber Messungen des Leuchtdichtefaktors an beliebige reflektierenden Proben , Lichttechnik, no. 11, 135A (1967).

Kartachevskaia, V.E. , and Skatchova , S.P. , New determination of reflection and luminance factors (in Russian), Svetotechnika , no. 1, 16 (1966).

Goebel, D.G. , Caldwell, B.P. , and Hammond, H.K. , Use of an auxiliary sphere with a spectroreflectometer to obtain absolute reflectance, JOSA, 56, 783 (1966).

Morren, L. , Mesure absolue des facteurs de luminance et de réflexion, Lux, no. 45, 448 (1967).

10.

Morren, L. , L'influence des ouvertures des surfaces planes et des écrans dans la mesure des facteurs de réflexion diffuse et de transmission diffuse par sphère intégratrice , Revue E, no. 3, 67 and no. 4, 119 (1969).

11.

Grum, F. , and Luckey, G.W. , Optical sphere paint and a working standard of reflectance, Applied Optics, 7, no. 11, 2289 (1968 ).

12.

Budde, W. , Standards of reflectance, JOSA, 50, 217 (1960).