新真空太阳望远镜多波段高分辨率成像系统的视场定标

Field Calibration of Multiband High Resolution Imaging System with New Vacuum Solar Telescope

为了实现新真空太阳望远镜(NVST)多波段图像0.1″精度的视场匹配,提出了针孔光阑视场定标的方法,并在NVST光球[TiO(705.8nm)]通道和色球[Hα(656.28nm)]通道上进行了实验分析。采用11×11点阵的针孔阵列光阑,对两通道视场之间的旋转、放缩和平移关系进行了定标。通过仿射变换实现两通道太阳图像的高精度视场匹配,精度可达0.031″。虽然匹配残差在整个视场内(约为2′)存在不均匀性,视场边缘最大残差为0.076″。定标参数的数值会随着光学平台位置的变化而改变,造成了0.05″的视场匹配差异,但这些匹配差异都在分辨率要求的精度之内。对TiO通道和Hα通道实测数据的分析也证明了上述方法的精度估计。

To achieve the filed matching of multiband images obtained by new vacuum solar telescope（NVST）with a high accuracy of 0.1″,a method called pinhole aperture filed calibration is proposed and applied to the experimental analysis about the photosphere[TiO（705.8 nm）]channel and chromosphere[Hα（656.28 nm）]channel of NVST.A pinhole-array aperture（11×11 pinholes）is used to the calibration of the rotation,scaling and translation relationships between the fields of the two channels.As a result,the high accuracy field matching of two-field solar images with the accuracy reaching up to 0.031″is accomplished by affine transformation.It is also found that the matching residual is not uniform in the entire field（about 2′）and the maximum residual is about 0.076″at the edge of the filed.The values of the calibration parameters are changing with the variation of optical platform position,and the matching difference of filed is 0.05″,which is within the precision of the resolution requirement.The estimated accuracy is also supported by the analysis of measured data from TiO channel and Hαchannel.