弹光调制型成像光谱偏振仪中的高精度偏振信息探测研究

The research of polarized information detection for photo-elastic modulator-based imaging spectropolarimeter

提出了一种基于三弹光调制器的差频偏振调制方法,并结合声光可调谐滤波技术构成了新型弹光调制型成像光谱偏振探测仪(photo-elastic modulator-based imaging spectro-polarimeter,PEM-ISP).介绍了PEM-ISP及三弹光差频偏振调制方法的基本工作原理,并从PEM-ISP的探测原理出发,通过分析和计算PEM-ISP的Mueller矩阵,推导出了相应的偏振测量公式;通过仿真及实验验证了三弹光差频偏振调制方法的可行性和准确性;最后分析了探测积分步长、采样间隔的选取对偏振测量的影响,对入射视场角、相位延迟幅值等因素所带来的测量误差进行了初步分析.结果表明,1%的相位延迟量误差带来的线偏振度DoLP误差<0.6%.本研究为新型PEM-ISP的遥感探测以及Stokes参量的反演的进一步工程化实现提供了必要的理论依据.

A new method of polarization modulation based triple-photoelastic-modulator （triple-PEM） is proposed as an key component of photo-elastic modulator-based imaging spectro-polarimeter （PEM-ISP） combined with acousto optic tunable filter. The basic principles of PEM-ISP and triple-PEM-based differential frequency polarization modulation are described, that is, the tandem PEMs are operated as an electro-optic circular retardance modulator in a high-performance reflective imaging system. Operating the PEMs at slightly different resonant frequencies generates a differential signal that modulates the polarized component of the incident light at a much lower heterodyne frequency. Then the basic equations for polarization measurement is derived by analyzing and calculating its Muller matrix. The simulation and experiments verify the feasibility and accuracy of polarization measurement by triple-PEM-based differential frequency polarization modulation. Finally, we analyze the influences of the setting of integral step and sampling interval of the detector polarization measurement, and a preliminary error analyses of field angle, phase retardation amplitude etc are also be carried out. The result shows that the measurement error of DoLP is less than 0.6% when the phase retardation error is 1%. This work provides the necessary theoretical basis for remote sensing of new PEM-ISP and for engineering implementation of Stokes parametric inversion.