LCVR和AOTF的光谱偏振测量新策略

摘要

现有利用液晶相位可变延迟器（LCVR）和声光可调谐滤光器（AOTF）的偏振测量方法较为繁琐，故提出了一种光谱偏振测量新策略，去除了机械运动，并且相位延迟量的选取从四组减少为两组。采用两个LCVR和一个AOTF ，通过两个相同型号探测器分别测量±1级衍射光，实现光谱偏振测量。电脑控制LCVR和AOTF的驱动系统分别实现所需相位延迟量和波长选择，通过扫描射频驱动整个频段得到被测光的光谱信息。叙述了方法的具体原理，分析了AOTF的偏振模型，通过理论计算LCVR和AOTF的Muller矩阵，推导出了相应的斯托克斯（Stokes）矢量中的 I ，Q ，U的测量公式。分析并仿真了相位延迟量微小偏差对整个系统测量误差的影响，结果显示相位延迟量在±π／100范围内相对误差＜3％。实验验证了测量系统的可行性和准确性，测量误差总体＜6％。为偏振测量提供了一种简单可行且精度较高的新方法，具有重要的应用价值。%In view of the existing relatively cumbersome polarization measurement method of using liquid crystal phase variable retarder (LCVR) and acousto‐optic tunable filter (AOTF) ,a new strategy of spectrum and polarization measurement is put for‐ward .This method removed mechanical movement and reduced the amount of phase delay from four groups to two groups .This method realizes the spectrum and polarization measurements by measuring the plus and minus 1 level diffraction light of the sys‐tem with two LCVR ,one AOTF and two same version detectors .For the polarization measurement of a particular wavelength , the computer controlled LCVR driving voltage to achieve the required phase delay in accordance with the requirements of the wavelength ,it also controlled the driving frequency to implement the required wavelength selection of AOTF .Because of the dif‐ferent driving frequencies of AOTF corresponding to the different wavelengths ,so it can get the spectral information by scanning the whole frequency bands ,In this paper detailed principles are deduced and the polarization model of AOTF is analyzed ,it also deduced the measurement formula of I ,Q ,U in the corresponding Stokes parameter through the theoretical calculation Muller matrix of the LCVR and AOTF .Finally it analyzed and simulated the measurement error of the whole system which was caused by the tiny deviation of phase delay ,the simulation results show that relative error <3% when the phase delay amount within the range of ±π/100 .This experiment proved the feasibility and accuracy of the measurement system ,the results show that the error of the measuring system overall <6% .This study provides a new method of polarization measurement which is simple , feasible and precise ,it has important application value .