论文标题
关于指向抖动,执行器漂移,望远镜卷和宽带探测器的影响,深孔维护和电场订单减少
On the Effects of Pointing Jitter, Actuators Drift, Telescope Rolls and Broadband Detectors in Dark Hole Maintenance and Electric Field Order Reduction
论文作者
论文摘要
预计太空冠状会检测到至少比宿主恒星比宿主恒星至少1e10倍的外植物。然而,实际检测阈值取决于仪器的波前稳定性,并且随着观察策略和后处理方法的选择而变化。在本文中,作者考虑了先前引入的观察策略(深孔维护)和后处理算法(电场降低)的性能。特别是,将表明,在某些常见的假设下,望远镜的平均指向抖动会转化为与恒星的残留光(Speckles)的额外光源不一致,并且可以在后处理中识别出抖动的“模式”,并与行星信号区分开来。我们还表明,通过使用电场结合(EFC)对图像高对比度区域的电场(Dark Hole)中电场的递归估算,可以减轻由于可变形镜执行器中电压漂移而导致的对比度下降。此外,即使测得的强度是宽带,只要它通过不连贯的单色强度总和可以很好地近似,就可以做到这一点。最后,我们通过对宽场外红外调查望远镜(WFIRST)的数值模拟来评估闭环与开环观测方案的性能。特别是,我们比较了有或没有电场阶数减少(EFOR)的角度差成像(ADI)的后处理因子,我们将其扩展到可能的望远镜卷和指向抖动的存在。对于本文考虑的所有观察参数,近环的深孔维护导致后处理的准确性明显更高。
Space coronagraphs are projected to detect exoplantes that are at least 1e10 times dimmer than their host stars. Yet, the actual detection threshold depends on the instrument's wavefront stability and varies by an order of magnitude with the choice of observation strategy and post-processing method. In this paper the authors consider the performance of the previously introduced observation strategy (dark hole maintenance) and post-processing algorithm (electric field order reduction) in the presence of various realistic effects. In particular, it will be shown that under some common assumptions, the telescope's averaged pointing jitter translates into an additional light source incoherent with the residual light from the star (speckles), and that jitter "modes" can be identified in post-processing and distinguished from a planet signal. We also show that the decrease in contrast due to drift of voltages in deformable mirror actuators can be mitigated by recursive estimation of the electric field in the high-contrast region of the image (dark hole) using Electric Field Conjugation (EFC). Moreover, this can be done even when the measured intensity is broadband, as long as it is well approximated by an incoherent sum of monochromatic intensities. Finally, we assess the performance of closed-loop vs. open-loop observation scenarios through a numerical simulation of the Wide-Field Infra-Red Survey Telescope (WFIRST). In particular, we compare the post-processing factors of Angular Differential Imaging (ADI) with and without Electric Field Order Reduction (EFOR), which we extended to account for possible telescope rolls and the presence of pointing jitter. For all observation parameters considered in this paper, close-loop dark hole maintenance resulted in significantly higher post-processing accuracy.