Dispersion of faraday rotation in fused quartz

Abstract

The complete experimental set-up of an accurate photoelectric polarimeter with an ultraviolet sensitive photomultiplier, a tuned amplifier followed by a cathode-ray oscillograph has been described in this paper. This has been used for the measurement of Faraday rotation in a perfect fused quartz specimen showing no residual birefringence. Measurements have been made for number of wavelengths λ 5780 to λ 2848 A. The following dispersion formula for magneto-optic rotation which fits the experimental data to 1/2% has been proposed using the same absorption frequencies that are responsible for refractive dispersion, $$V = {e \over {2mc^2 }}{1 \over n} \times 0 \cdot 793\left[ {{{0 \cdot 001915 \lambda ^2 } \over {(\lambda ^2 - (0 \cdot 0600)^2 )^2 }} + {{0 \cdot 004664 \lambda ^2 } \over {(\lambda ^2 - (0 \cdot 1060)^2 )^2 }} + {{0 \cdot 002223 \lambda ^2 } \over {(\lambda ^2 - (0 \cdot 1190)^2 )^2 }}} \right]$$ where V is in radians and λ in microns. The magneto-optic anomaly factor is 0·793 for all the absorption frequencies. The available data on crystalline quartz has also been analysed and the values of the Verdet constant, the magneto-optic anomaly factor and the magnetic rotativity of the two substances have been compared and found to be significantly different.