宽谱段高光谱成像仪星上波长定标方法

Method of in-flight wavelength calibration for wide band hyper-spectral imager

高光谱成像探测仪在轨波长漂移和性能衰变是有效载荷在轨长期工作必须解决的问题。利用太阳辐射光谱和大气后向散射辐射光谱中特有的Fraunhofer吸收线可作为星上波长定标的基准。针对波长定标精度需求,优选出高精度的太阳参考光谱,用仪器狭缝函数卷积后初选出87条Fraunhofer吸收线,并分析了由Fraunhofer吸收线分布非均匀性引起的系统误差,以及由仪器探测能力不同而产生的随机误差。综合最大偏差和RMS,确定了在满足定标精度优于0.01 nm的条件下,可用的76条太阳Fraunhofer线的精确位置。该研究为高光谱成像探测载荷在轨高精度波长定标奠定了基础。

The wavelength drift and perfo rmance decay of hyper-spectral imager are the main problems that must be solved for long-term operation in orbit.The Fraunhofer absorption line,which is unique in the solar radiation spectrum and the atmospheric backscattering radiation spectrum,can be used as the benchmark for the wavelength calibration.According to the requirement for wavelength calibration precision of instrument,the high precision solar reference spectrum was optimized,then 87 Fraunhofer absorption lines were selected by the convolution of instrument slit function.The system error caused by the line asymmetric and the random error ca used by the instrument detection capabilities were analyzed.Based on maximum deviation and RMS,the exact positions for available 76 solar Fraunhofer lines were determined under the condition that the calibration accuracy was better than 0.01 nm.This study lays the foundation for high precision wavelength calibration of hyper-spectral imaging on-orbit.