| 其他摘要 | In order to study the fine structure of solar photosphere and chromosphere, we need to obtain high-resolution images. But the existence of the atmospheric turbulence makes the large ground-based telescope can’t realize the diffraction limited imaging. NVST(New Vacuum Solar Telescope) choose the widely used High-resolution Statistical Reconstruction Method to overcome the influence of atmospheric turbulence, to obtain high-resolution solar images. High-resolution Statistical Reconstruction Technology is easy to implement, but have large amount of calculation, especially for synchronous collection of multi-channel solar telescope, large data quantity gives great pressure on later data processing. For reasons such as narrow bandwidth and so on, halpha channels’ SNR is a little low, this will affect the reconstruction accuracy of high frequency. Simultaneously, its exposure time is long, about 20 ms, and this will smooth high frequency information, thus affect the reconstruction accuracy. Multi-channel reconstruction using the point spread function of a single channel to rebuild other channels, can effectively shorten the data processing time, if we use the high SNR channel to reconstruct the low SNR channel, will also to a certain extent, improve the image reconstruction accuracy. The key of image reconstruction is to obtain the precise point spread function. High-resolution Statistical Reconstruction Method using the estimated seeing parameter to estimate PSF, haven’t consider the aberration of telescopic and have cut-off high frequency information. In the paper we presented a method based on wavefront detection to achive the PSF, but it is difficult to realize in wide field of wavefront detection, then, we proposed another method based on the results of the statistical reconstruction, which containing the telescope aberration and high frequency information. After getting the accurate PSF of a channel, make some correction on the wavelength, and then realize the reconstruction of the multi-channel. We have successfully done the simulation experiment of multi-channel high resolution reconstruction, in addition, analyzed the impact of the noise and the aberration between channels on the reconstruction result. Multi-channel High-resolution Reconstruction was done on the hypothesis that rays of all channels have passed through the same atmospheric path, however, the atmospheric dispersion will make light of different wavelengths pass through different atmospheric paths, so that they are affected by different atmosphere. The differences of the wavefront aberration between these channels caused by dispersion will inevitably affect the result of the multi-channel reconstruction, so, at the last part of this paper, simulation analysis has been done for the impact on multichannel reconstruction under different observation zenith Angle dispersion. |
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