基于外差干涉技术测量液体费尔德常数的实验研究

摘要

为了准确测量液体的费尔德常数,设计搭建了一套外差干涉实验系统,主要包括MachZehnder干涉光路、声光调制器(AOM)及锁相放大器.葡萄糖溶液测量结果显示,其费尔德常数随其浓度的增加而有变化的趋势.此外,加正与负磁场所测得的费尔德常数并不相等,其原因是加正磁场造成葡萄糖分子的形变与加负磁场所造成葡萄糖分子的形变不同,形变大其费尔德常数也就越大.蔗糖溶液测量结果发现,在加正与负磁场时所得的费尔德常数没有明显变化,其原因是蔗糖水解时产生了右旋葡萄糖和左旋果糖,使得形变效应相互抵消.%In order to precisely measure the Verdet constant of liquids, an optical heterodyne interference system is designed and constructed, which is to be combined with a Mach-Zehnder interferometer, an AOM and a lock-in amplifier. The measured result of glucose solution shows that the measured values of Verdet constant change with the concentration. In addition, Verdet constants for the positive applied magnetic field are different from the ones for the negative applied magnetic field. The reason of this difference is that the deformation of glucose molecule caused by a positive magnetic field is different from that caused by an applied magnetic field, and a larger deformation produced a bigger Verdet constant. The measured results of sucrose solution show that Verdet constants for the positive and negative applied magnetic fields do not display obvious change. The reason is probably that dextroglucose and L-sucrose are produced by sucrose hydrolysis and deformation effects are counterbalanced.