暗电流对短波红外偏振测量精度的影响

探测器暗电流及其测量不确定度是影响短波红外偏振测量仪器测量精度的最重要因素。首先,结合红外探测器的工作原理,分析并建立了暗电流影响下的红外探测系统噪声模型。根据分析结果设计实验获得短波红外探测器G5853-21暗电流与温度和反向偏压关系。然后,以分孔径偏振探测系统为例,推导了斯托克斯参数误差模型和偏振度误差模型。最后,重点分析空间环境应用背景下,针对暗电流影响的改进措施,提出了探测器精确温控的暗电流影响改进方案,并给出了短波红外探测器工作温度指标要求。结果表明:通过对探测器进行精确的温度控制以降低暗电流数值,可以将包含暗电流测量不确定度和其他噪声引起的偏振度测量误差控制在0.42%(=0.3时)以内。

Impact of dark current on SWIR polarimetry accuracy

The variation of dark current is the key factor influencing the accuracy of the signals of detectors in the short-wave infrared(SWIR) band. Firstly, based on the analysis of the working principle of infrared detector G5853-21, an experiment was designed aiming to find the relation between dark current, temperature and reverse bias of the detector. Also, an error model was given for the infrared polarimeter by considering the influences of dark currents. Error models for Stokes parameters and the degree of polarization have been built for the polarimeter. Allowing for the specific conditions in the space environment,an optimization was designed to reduce the impacts of dark currents and temperature requirement was also given for the infrared polarimeter. The results indicated that, with accurate control of the temperature, the error of the degree of polarization, involving the measurement uncertainity and other noises, could be below 0.42%(with =0.3).