Abstract: Inspired by Malus' s Law，an optical path is designed in the Faraday rotation experiment to
simultaneously collect optical power data of two light beams:one passing through a magneto-optical crystal and
the other bypassing it．Plotting these two datasets yields an elliptical pattern．The shape of the ellipse reflects the
phase difference between the two optical paths，which has a quantitative relationship with the magneto-optical
rotation angle of the sample．The Verdet constant of the sample can be obtained by measuring the magneto-
optical rotation angles under different magnetic fields using the above phase-comparison method．Compared with
the commonly used double-extinction method for measuring rotation angles in teaching，this new method does
not require recording the specific readings of the analyzer and is unaffected by the angular precision of
polarizers．Meanwhile，the phase-comparison method can deepen students' understanding of the polarization
characteristics of light and provide a supplementary experimental approach for measuring the Verdet constant of
media．
张蔓荻, 许 杭, 杨大为, 黄玉迪, 罗锻斌 . 测量磁光介质费尔德常数的一种新方法[J]. 大学物理实验, 2026, 39(5): 50-54.
ZHANG Mandi, XU Hang, YANG Dawei, HUANG Yudi, LUO Duanbin. A New Method for Measuring the Verdet Constant of Magneto-Optical Media#br#. Physical Experiment of College, 2026, 39(5): 50-54.
