直接观测太阳在轨辐射定标技术研究

发布时间：2018-08-22 15:26

【摘要】：星上定标技术是保障遥感器定量化应用的有效手段,目前基于漫射板的星上定标技术已经趋于成熟,其中MODIS以2%～4%的星上定标精度被公认为是最高水平。气候变化预测和在轨交叉定标等方面研究需要更高的星上定标精度,但是漫射板受自身反射特性变化的影响,使定标精度的进一步提高受到了限制。为满足科学研究需求,国际上提出了直接观测太阳的在轨辐射定标方法。该方法避免了因漫射板自身衰变而引起的定标不确定度,有可能使星上定标精度得到一个量级的提升。本文开展了直接观测太阳的在轨辐射定标方法探索,设计了定标的总体技术方案,根据定标过程中观测目标的特点,研究了该定标方案所需要的大范围衰减太阳光的方法,并对衰减因子进行测试。首先,论文计算了该定标方法的典型观测目标辐亮度,并对结果进行比较得出直接观测太阳在轨辐射定标需要将太阳光衰减5个量级;根据需要的衰减倍数,研究了组合衰减和多孔板衰减两种太阳光衰减方法,其中组合衰减法通过减小孔径光阑面积、减小探测器积分时间和加入中性滤光片共同达到衰减要求;多孔板衰减法利用遮挡和衍射来实现衰减。然后,对组合衰减法的衰减因子进行测量,得出组合衰减法可以实现5个量级的衰减,满足直接观测太阳星上定标的衰减要求。最后,论文对本次研究的进展以及不足之处进行总结,并提出下一步的研究内容。
[Abstract]:On-board calibration technology is an effective means to guarantee the quantitative application of remote sensor. At present, the onboard calibration technology based on diffuse plate has become mature, and MODIS is recognized as the highest level with 2% of on-board calibration accuracy. The prediction of climate change and the cross calibration in orbit need higher calibration accuracy on satellite, but the diffusion plate is affected by the change of its own reflection characteristics, so the further improvement of calibration accuracy is limited. In order to meet the needs of scientific research, a calibration method for direct observation of the sun in orbit is proposed. This method avoids the uncertainty of calibration caused by the decay of the diffusion plate and may improve the calibration accuracy by an order of magnitude. In this paper, the method of direct observation of the solar radiation calibration in orbit is explored, and the overall technical scheme of calibration is designed. According to the characteristics of the observation object in the calibration process, the method of attenuating the solar light in a large range is studied in the light of the characteristics of the observation object in the calibration process. The attenuation factor was tested. First of all, the radiance of the typical observation object of the calibration method is calculated, and the results are compared. It is concluded that the solar radiation calibration for direct observation of the sun in orbit needs to attenuate the solar light by 5 orders of magnitude, according to the attenuation times required, Two kinds of solar attenuation methods, combined attenuation and perforated plate attenuation, are studied. The combined attenuation method can achieve the attenuation requirements by reducing the aperture area, reducing the integral time of the detector and adding the neutral filter. The attenuation of perforated plates is realized by means of occlusion and diffraction. Then, the attenuation factor of the combined attenuation method is measured, and it is concluded that the combined attenuation method can realize the attenuation of five orders of magnitude, which can meet the attenuation requirements of direct observation of the solar star calibration. Finally, the paper summarizes the progress and shortcomings of this study, and puts forward the next research content.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP73

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