考虑偏振片非理想性的可见光偏振成像修正模型

常用的偏振成像理论模型大多基于理想偏振片假设,即偏振片的消光比为无穷大且主方向已知,而实际偏振片的非理想性会对偏振成像系统的测量精度产生明显的影响,为降低这种影响,对考虑偏振片非理想性的偏振成像模型进行研究。以基于斯托克斯矢量的偏振成像模型为基础,通过分析实际偏振片对入射光偏振态的改变,提出了一种考虑偏振片非理想性的可见光偏振成像修正模型,给出了考虑实际偏振片性能及主方向误差的偏振度、偏振角修正公式。利用分时偏振成像系统对线偏振光的偏振度进行测量,实验结果表明:当偏振片消光比为100:1时,理想模型的线偏振光偏振度测量的平均相对误差为5.53%,修正模型的偏振度测量的平均相对误差降低到3.62%。应用该修正模型可在使用低消光比偏振片时达到与高消光比偏振片相当的偏振度测量精度,使偏振成像系统能够拥有更大视场,成本降低。

Correction model for visible light polarization imaging considering non-ideality of polarizers

Current theoretical polarization imaging models are based mostly on the assumption of ideal polarizers whose extinction ratio is significantly large and whose main direction is already known.However,the actual non-ideality of polarizers will have a significant impact on the accuracy of polarization imaging measurements.A correction model of visible light polarization imaging considering the non-ideality of polarizers was investigated to decrease this impact.Based on the Stokes vector polarization theory,a correction model of visible light polarization imaging considering the non-ideality of the polarizer was proposed by analyzing the change of the polarization state of the incident light caused by the actual polarizer.The corresponding calculation formulas for the degree of linear polarization(DoLP)and angle of polarization(AoP)were given.An experiment measuring the DoLP of the incident linearly polarized light via a time-division polarization imaging system was conducted.When the extinction ratio of the polarizer is 100:1,the average relative error of the DoLP based on an ideal model is 5.53%,while the average relative error of the DoLP based on the correction model is reduced to 3.62%.Results show that the proposed correction model can effectively improve the accuracy of polarization information measurements.Using the proposed correction model can achieve a high DoLP measurement accuracy when the measurement system is constructed by a low extinction ratio polarizer.Furthermore,a larger field of view can be obtained at a lower cost.