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Direct measurement of standard reflectances with the microphotometer

Published online by Cambridge University Press:  14 March 2018

A. F. Hallimond
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Summary

A visual microphotometer depending on three polarizing screens is used to provide the primary scale for measuring the ratio of intensity between the incident and reflected beams for a prepared standard surface, which is intended for subsequent use in the ordinary procedure with the ore-microscope. A reversing mirror on the microscope stage gives reflection at quasi-normal incidence. Direct measurements on a surface of diamond confirm the validity of the Fresnel formula for a polished surface of this substance, and there is general agreement for a series of transparent bodies ranging up to 17 % reflectance. The standard is a glass-covered metallic surface with a reflectance near 50 %. For pyrite RD = 54·5 %.

Type
Research Article
Information
Mineralogical magazine and journal of the Mineralogical Society , Volume 31 , Issue 237 , June 1957 , pp. 487 - 494
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 1957

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References

Bailey, (A. I.) and Seal, (M.), Industr. Diamond Rev., 1956, vol. 16, p. 145.Google Scholar
Hallimond, (A. F.), Manual of the Polarizing Microscope, 2nd edn, 1953 (reprinted ). York; Cooke, Troughton, and Simms.Google Scholar
Ramdohr, (P.), Die Erzmineralien..., Berlin, 2nd edn, 1955.Google Scholar
Steel, (W. H.), Journ. Opt. Soe. Amer., 1951, vol. 41, p. 223.CrossRefGoogle Scholar
Walsh, (J. W. T.), Photometry, 2nd edn, 1953. London, Constable.Google Scholar
Wiles, (E. M.), Journ. Opt. Soc. Amer., 1953, vol. 43, p. 84.Google Scholar