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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

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