Based On Faraday Rotation Effect Of Two-stage Modulation Polariscope Research And Design

Polarized light measurement technology used in industrial production monitoring， scientificresearch， medical instruments， and other fields importantly. Such as analysis of material verdetconstant， solution concentration measurement， displacement， film thickness measurement， controlmeasures， etc. Polarized optical Angle mostly measured by rotation. The volume weight of rotations onthe market is very high. The higher precision the more expensive. The problems mainly exists inmechanical measurement and the photomultiplier tube. How to replace servo motor significantly reducingrotation volume and weight， how to improve the precision and speed of the photoelectric detector， that iswhat we focus in the study of this article.In front of the paper， the polarization of the light principle， the principle of linear polarized light，the optical effect， magneto optical effect theory， magneto optical applications and related books andliterature have been seen. Changchun institute of applied chemistry， Chinese academy of sciences，studied the Faraday magneto-optic effect measurement，Harbin engineering university in2011made a tinymagnetic rotation Angle measurement experiment，2012Shanghai university of science and technology byusing Faraday magnetic rotation photosynthetic efficiency with FFT algorithm to achieve the measurementof low concentration solution，etc. In this paper，based on the study of The above research，liquid crystalrotation， acousto-optic modulation polariscope， colored light/rotation frequency converter and manyother kinds of rotation be comparatived. Through theoretical analysis and experimental verification，designed the Faraday rotation effect of two-stage modulation polariscope. This method not only can reducethe volume， and improve the measuring precision and speed. From theory and experiment， this paperdetailed Faraday rotation effect principle and dc ac two-stage modulation measuring optical rotation Angletechnology. The main characteristic is using the Faraday rotation effect of two-stage modulation measurement system. The first level， rotation Angle calibration， changing the dc current to change thesize of the magnetic rotatory Angle， so that the light vector reverse rotation to extinction position，measuring the rough side Angle. The original converted into current measured by the motor rotating， soreduced the original motor rotating mechanical error brought by the influence of solution concentrationmeasurement; The second level， the small Angle measurement， on the basis of dc superimposed accurrent modulation signal to the rest of the Angle measurement， the DSP used to the output of thephotodetector modulation signal data acquisition and processing， measuring the precise small Angle value.Last， two measuring Angle value stack operation get measured precision rotation Angle.In this paper， the design of rotation basically achieved the desired accuracy of measurement， theprecision can be controlled below0.01°. The method can not only measure optical rotation Angle quicklyand accurately， but also can make system design more miniaturization and apparatus.