Optical Performance Test And Simulation Of Heavy Metal Magneto-optical Glass

Heavy metal Magneto-optic Glass is a kind of excellent current sensing material.It can detect the current by using the rotation characteristic of polarization plane affected by external magnetic field.It has an important application in the field of industrial high current measurement.Due to the bright future of magneto-optical current transformers(MOCT),it is necessary to study the core module,namely the magneto-optical glass sensing mechanism,and the influence of magnetic field,temperature,thermal stress,fluid cooling,etc.on its performance.In this paper,the preparation process of a PB system for diamagnetic magneto-optical glass was firstly studied.Glass samples of various specifications and compositions were prepared,and their structure and performance indexes were characterized by Raman spectroscopy,Fourier transform infrared(FT-IR)spectroscopy and X-ray diffraction(XRD).The glasses have the advantages of large Verdet constant,simple preparation and excellent thermodynamic performance.In addition,the temperature dependence data of Verdet constant was obtained by using the variable temperature magneto-optical measurement platform designed by our laboratory.In view of some blanks in the previous research on the diamagnetic glasses,we have made a deep study on the phenomenon that the Verdet constant decreases with the increase of temperature.We obtained an empirical formula by fitting the Verdet–temperature curve,and a good theoretical explanation from the perspective of thermal expansion coefficient and glass structure is given,which provides an evaluation basis and data support for further development of MOCT materials.Based on the finite element method and COMSOL simulation software,we modeled the magneto-optical sensing micro-element,and successfully realized the multi-physics coupling of magnetic field,light field,temperature field,stress field and fluid flow.The evolution of the electric field component of the incident light in the Faraday effect is studied,and the validity of the model is verified.Finally,this paper qualitatively analysed the influence of temperature on the accuracy of measurement in real environment.The simulation data proved that the external heat source will cause the internal stress of the magneto-optical glass to be uneven,the refractive index of different spindles changed,and the surface of glass would be deformed and displaced,the resulting phase difference will reduce the magneto-optical rotation angle.According to the simulation comparison under different fluid velocity conditions,we gave some suggestions for reducing the influence of thermal stress birefringence in practical applications.