相位分集图像重建技术对圆偏振不对称性的影响
Influence of phase-diversity image reconstruction techniques on circular polarization asymmetries
摘要：
全斯托克斯滤波偏振仪是研究太阳表面磁结构快速演化的关键仪器。为此，通常使用后验图像重建方法来提高图像质量。我们分析了相位分集图像重建技术的圆偏振不对称的鲁棒性。我们使用不同初始条件下的磁流体动力学模拟的快照来合成5250.2A处的磁敏感Fe I线的光谱。我们降低合成的配置文件的空间和光谱模拟观测与IMAX全斯托克斯滤波器偏振。我们还模拟了用于重建和极化调制方案的相位分集算法的聚焦/散焦图像对。我们假设标准的优化方法能够以10%的精度推断波前在泽尼克多项式上的投影。我们还考虑了25%精度的不太有利的情况。我们获得重建的单色调制图像，稍后解调，并与原始地图进行比较。虽然不对称性往往很难定义在安静的太阳由于斯托克斯V配置文件的复杂性，我们展示了如何不对称性与空间和光谱拖尾退化。结果表明，虽然图像重建技术减少了空间拖尾，但它们可以修改主要由空间相关噪声的出现引起的轮廓的不对称性。
英文摘要：
Full Stokes filter-polarimeters are key instruments for investigating the rapid evolution of magnetic structures on the solar surface. To this end, the image quality is routinely improved using a-posteriori image reconstruction methods. We analyze the robustness of circular polarization asymmetries to phase-diversity image reconstruction techniques. We use snapshots of magneto-hydrodynamical simulations carried out with different initial conditions to synthesize spectra of the magnetically sensitive Fe I line at 5250.2 A. We degrade the synthetic profiles spatially and spectrally to simulate observations with the IMaX full Stokes filter-polarimeter. We also simulate the focused/defocused pairs of images used by the phase-diversity algorithm for reconstruction and the polarimetric modulation scheme. We assume that standard optimization methods are able to infer the projection of the wavefront on the Zernike polynomials with 10% precision. We also consider the less favorable case of 25% precision. We obtain reconstructed monochromatic modulated images that are later demodulated and compared with the original maps. Although asymmetries are often difficult to define in the quiet Sun due to the complexity of the Stokes V profiles, we show how asymmetries are degraded with spatial and spectral smearing. The results indicate that, although image reconstruction techniques reduce the spatial smearing, they can modify the asymmetries of the profiles, mainly caused by the appearance of spatially-correlated noise.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
