The optical constants of crystal quartz in the far infrared (10–400 cm−1) are presented along with the dispersion parameters for the two ordinary-ray bands measured in this study. The asymmetric Fourier-transform method was used for the quantitative measurement of the refractive indices of quartz. The advantages of this method as compared with the channeled-spectrum method usually employed for refractive-index measurements in the far infrared are discussed. The extrapolated, zero-frequency refractive indices of quartz are n0(0)=2.106±0.001 and ne(0)=2.154±0.001. A pseudocoherence effect is described which permits the measurement of the difference of the principle refractive indices in a birefringent sample without the use of a polarizer.
© 1967 Optical Society of America
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