空间调制线偏振光谱测量的误差影响仿真分析

Analysis for Influence of Element Deviation to DOLP Measured by Spatial Modulating Spectropolarimeter

通过理论推导,给出了1/4波片复合双折射光楔偏振片型空间调制结构的误差矩阵,并在空间调制相位为0及0.5π的位置分别计算了理想像面光强受器件误差的影响程度。1/4波片的延迟量误差是将入射光斯托克斯参量的V分量引入调制光强中的主要原因,在调制相位为0.5π的位置,当延迟量误差为0.02π时,其调制系数为0.0314。在给定的器件误差范围内,入射斯托克斯参量具有同样的Q、U分量时,V=0.2会使得U分量测量偏差控制在0.45%内的概率从V=0时的80%左右下降到6%。利用计算机仿真分析得到了线偏振度测量偏差随入射条件的变化,在所有误差取误差范围内的最大值且入射光的V分量小于0.04时,在仪器未定标的条件下,线偏振度的相对测量偏差可以控制在0.5%以内。

Matrix of deviation for spatial modulating spectropolarimeter that composed of quarter wave plate, double birefringent wedges and polarizer is educed. Magnitude of influence of element deviation to emergent light is figured out, with that the modulative phase retardance is equal to 0 or 0.5π. It is presented that, when retardant phase is 0.5π and its deviation is 0. 027π, the modulating coefficient of Stokes parameter V is 0. 0314. And when V=0.2, it will cause that the probability of restraint for measuring deviation of Stokes parameter U under 0.45 %, is decreased from about 80% to 6%, compare with V=0. By simulation analysis, it is presented that the relative measuring deviation of degree of linear polarization （DOLP） is less than 0.5 % without instrument polarization calibrating, when all the element deviations are equal to the positive maximum in their span of deviation, and the Stokes parameter V≤0.04.