Refractive properties of magnesium fluoride

Abstract

The refractive indices of a commercially available specimen of single-crystal MgF₂ were determined for both the ordinary and extraordinary rays at selected wavelengths from 0.2026 to 7.04 μm. Measurements were made by means of the minimum-deviation method on a precision spectrometer near 19°C. The experimentally determined index values for each polarization were fitted to a three-term Sellmeier-type dispersion equation of the form $n^2-1=\sum A_j{\mathrm{\lambda }}^2({\mathrm{\lambda }}^2-{\mathrm{\lambda }}_j^2)$, where n is the refractive index, λ is the wavelength of interest, λ_j is the calculated wavelength of an oscillator, and A_j is the strength of the oscillator at λ_j. The birefringence was computed as a function of wavelength from the calculated index values obtained for the two polarizations. The dispersion coefficients were also determined for the 0 ray and for the birefringence. The results of this study are compared with previously reported work on the refractive properties of MgF₂.

© 1984 Optical Society of America

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