High-order wavefront sensing and control (HOWFSC) is key to creating a dark hole region within the coronagraphic image plane where high contrasts are achieved. The Roman Coronagraph is expected to perform its HOWFSC with a ground-in-the-loop scheme due to the computational complexity of the electric field conjugation (EFC) algorithm. This scheme provides the flexibility to alter the HOWFSC algorithm for given science objectives. The baseline HOWFSC scheme involves running EFC while observing a bright star such as ζ Puppis to create the initial dark hole followed by a slew to the science target. The new implicit EFC (iEFC) algorithm removes the optical diffraction model from the controller, making the final contrast independent of model accuracy. While previously demonstrated with a single deformable mirror, iEFC is extended to two deformable mirror systems to create annular dark holes. First, an overview of both EFC and iEFC is presented. The algorithm is then applied to the wide-field-of-view shaped pupil coronagraph (SPC-WFOV) mode designed for the Roman Space Telescope using end-to-end physical optics models. Initial noiseless monochromatic simulations demonstrate the efficacy of iEFC as well as the optimal choice of modes for the SPC-WFOV instrument. Further simulations with a 3.6% wavefront control bandpass and a broader 10% bandpass then demonstrate that iEFC can be used in broadband scenarios to achieve contrasts below 10−8 with Roman. Finally, an electron multiplying charge-coupled device (EMCCD) model is implemented to estimate calibration times and predict the controller’s performance. Here, 10−8 contrasts are achieved with a calibration time of ∼6.8 h assuming the reference star is ζ Puppis. The results here indicate that iEFC can be a valid HOWFSC method that can mitigate the risk of model errors associated with space-borne coronagraphs, but to maximize iEFC performance, lengthy calibration times will be required to mitigate the noise accumulated during calibration.

中文翻译：

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罗马日冕仪上两个变形镜隐式电场共轭的建模和性能分析

高阶波前传感和控制 (HOWFSC) 是在冠状图像平面内创建黑洞区域并实现高对比度的关键。由于电场共轭 (EFC) 算法的计算复杂性，罗马日冕仪预计将采用接地环路方案来执行 HOWFSC。该方案提供了针对给定科学目标改变 HOWFSC 算法的灵活性。基线 HOWFSC 方案涉及运行 EFC，同时观察明亮的恒星（如 δ Puppis）以创建初始黑洞，然后转向科学目标。新的隐式 EFC (iEFC) 算法从控制器中删除了光学衍射模型，使最终对比度与模型精度无关。虽然之前使用单个可变形反射镜进行了演示，但 iEFC 已扩展到两个可变形反射镜系统以创建环形黑洞。首先，概述 EFC 和 iEFC。然后将该算法应用于使用端到端物理光学模型为罗马太空望远镜设计的宽视场形状光瞳日冕仪（SPC-WFOV）模式。初始无噪声单色模拟证明了 iEFC 的功效以及 SPC-WFOV 仪器的最佳模式选择。使用 3.6% 波前控制带通和更宽的 10% 带通进行的进一步模拟表明，iEFC 可用于宽带场景，以实现与 Roman 低于 10−8 的对比度。最后，采用电子倍增电荷耦合器件 (EMCCD) 模型来估计校准时间并预测控制器的性能。这里，假设参考星是 δ Puppis，则通过~6.8 h 的校准时间实现 10−8 对比。这里的结果表明，iEFC 可以是一种有效的 HOWFSC 方法，可以减轻与星载日冕仪相关的模型错误风险，但为了最大限度地提高 iEFC 性能，需要较长的校准时间来减轻校准期间积累的噪声。