基于磁柱型轴向均匀磁场产生装置的法拉第磁致旋光仪及实验设计  

Faraday magneto-optical rotation instrument based on the axial uniform magnetic field generating device with magnetic columns and experimental design

作　　者：杨保东[1] 薛朝 周海涛[1] YANG Baodong;XUE Zhao;ZHOU Haitao(College of Physics and Electronic Engineering,Shanxi University,Taiyuan 030006,China)

机构地区：[1]山西大学物理电子工程学院,山西太原030006

出　　处：《实验技术与管理》2024年第7期134-139,共6页Experimental Technology and Management

基　　金：国家自然科学基金项目(61975102);山西省高等学校科技创新项目(2019L0101)。

摘　　要：该文改进了法拉第磁致旋光仪的轴向磁场产生装置,设计核心是将多个沿厚度方向充磁的圆柱形钕铁硼永磁铁对称地放置在待测样品周围,具有磁场空间分布稳定、轴向磁场均匀、大小灵活可调等优点。此外,提出采用“相位法”测量法拉第磁致旋光角,通过与“消光法”比较表明,“相位法”能显著提高测量精度,测量误差小于0.5°。改进的磁场产生装置和测量方法也可用于法拉第反常色散滤光器等磁光旋转科研实验。[Objective]The Faraday magneto-optical rotation instrument,commonly used to study the magneto-optical rotation effect,has a crucial component:the axial magnetic field generation device.Traditional methods for generating this magnetic field include electromagnets and energized solenoids,which,while easily adjustable by changing the electric current,are bulky and prone to large noise fluctuations.Therefore,improvements to the Faraday magneto-optical rotation instrument are necessary.In addition,traditional Faraday magneto-optical rotation experiments with the“extinction method”tend to have large errors owing to their insensitivity to light intensity changes at the extinction position.Therefore,exploring other methods to improve measurement precision is necessary.[Methods]In our Faraday magneto-optical rotation instrument,we improved the uniformity of the magnetic field by symmetrically placing magnetic columns around the test samples.These columns consist of many small cylindrical NdFeB permanent magnets magnetized along their thickness.The magnetic field’s strength can be conveniently adjusted by changing the number of magnetic columns.Compared with popular electromagnet devices,our designed magnetic field generator offers a stable magnetic field distribution and flexible magnitude adjustments.For precise measurement of Faraday magneto-optical rotation angle,we proposed and demonstrated a“phase method”instead of the traditional“extinction method.”This method measures the rotation angle as a laser passes through TGG crystals once or twice.We also used a laser with different wavelengths,namely 405,450,520,and 635 nm,to measure the Verdet constant of TGG crystals.[Results]Experimental data indicated that the uniformity of the magnetic field was in the region of 5 cm along the axis.Higher axial magnetic field strengths corresponded to better uniformity,with an experimental unevenness measured at about 2.5%when the magnetic field exceeded 500 Gs.The“phase method”significantly improved the measurement

关 键 词：法拉第磁光效应 均匀磁场 维尔德常数 

分 类 号：TN29[电子电信—物理电子学] O439[机械工程—光学工程]