Abstract

A grating monochromator based on the Czerny–Turner system and having 12-in.-diameter mirrors is used for measurements in a wavelength range from 40–300 μ. Indices of refraction of quartz and sapphire are determined by studying the channel spectrum observed in transmission of polarized radiation by 1-mm-thick plates. Results, extrapolated to zero frequency, are: n_0⊥=2.102, n_0‖=2.153 in quartz and n_0⊥=3.060, n_0‖=3.402 in sapphire to an accuracy of 0.1%. Dispersion and absorption are measured and are shown to be consistent with theory. An absorption band is observed in the ordinary ray in quartz centered at a wavelength of 78.0 μ and having a width of about 3μ. No other absorption anomaly is clearly distinguishable in any of the measurements.

© 1962 Optical Society of America

Optical Properties of Sapphire in the Far Infrared*

Ernest V. Loewenstein
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Edgar E. Russell and Ely E. Bell
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