论文标题

对速度和激烈的焦点平面波沿感测的天空验证:向前迈向控制Subaru/scexao的岛屿效应

On-sky verification of Fast and Furious focal-plane wavefront sensing: Moving forward toward controlling the island effect at Subaru/SCExAO

论文作者

Bos, Steven P., Vievard, Sébastien, Wilby, Michael J., Snik, Frans, Lozi, Julien, Guyon, Olivier, Norris, Barnaby R. M., Jovanovic, Nemanja, Martinache, Frantz, Sauvage, Jean-François, Keller, Christoph U.

论文摘要

岛屿效应(IE)可以限制外部球星的高对比度成像(HCI)观察结果。在当前的望远镜上,当地面风速低于每秒几米时,IE将成为一个严重的问题。这被称为低风效应(LWE)。 LWE严重扭曲了点扩散函数(PSF),显着降低了Strehl比率并降低对比度。在本文中,我们的目的是表明,焦点波前传感(FPWFS)算法,快速与激情(F&F)可用于测量和纠正IE/LWE。我们使用H波段中的内部近红外摄像头在Subaru望远镜的Scexao HCI仪器上部署了算法。我们用内部来源测试了F&F,并通过整个端到端系统和大气湍流进行了SKY部署以测试其性能。根据PSF质量,通过两个指标评估了该算法的性能:1)Strehl比率近似($ SRA $)和2)标准化第一个Airy环($ var $)的差异。随机LWE相屏幕在0.4 $ $ m和2 $μ$ m之间具有峰值到谷波之前误差,均被校正为$ SRA $ $> $> $ 90 \%\%和$ var \ lessapprox0.05 $。此外,天上的结果表明,F&F能够在非常具有挑战性的大气条件下提高PSF质量(1.3-1.4''在500 nm处看到)。闭环测试表明,F&F能够将$ VAR $从0.27提高到0.03,因此可以显着改善PSF的对称性。同时观察{光学}($λ= $ 750 nm,$δλ= $ 50 nm)中的PSF表明,在这些测试中,我们纠正了SCEXAO中的光学和NIR病常见的畸变。展望未来,该算法适用于观察模式,这将使科学观察期间具有更高质量和稳定性的PSF。

High-contrast imaging (HCI) observations of exoplanets can be limited by the island effect (IE). On the current generation of telescopes, the IE becomes a severe problem when the ground wind speed is below a few meters per second. This is referred to as the low-wind effect (LWE). The LWE severely distorts the point spread function (PSF), significantly lowering the Strehl ratio and degrading the contrast. In this article, we aim to show that the focal-plane wavefront sensing (FPWFS) algorithm, Fast and Furious (F&F), can be used to measure and correct the IE/LWE. We deployed the algorithm on the SCExAO HCI instrument at the Subaru Telescope using the internal near-infrared camera in H-band. We tested F&F with the internal source, and it was deployed on-sky to test its performance with the full end-to-end system and atmospheric turbulence. The performance of the algorithm was evaluated by two metrics based on the PSF quality: 1) the Strehl ratio approximation ($SRA$), and 2) variance of the normalized first Airy ring ($VAR$). Random LWE phase screens with a peak-to-valley wavefront error between 0.4 $μ$m and 2 $μ$m were all corrected to a $SRA$ $>$90\% and an $VAR\lessapprox0.05$. Furthermore, the on-sky results show that F&F is able to improve the PSF quality during very challenging atmospheric conditions (1.3-1.4'' seeing at 500 nm). Closed-loop tests show that F&F is able to improve the $VAR$ from 0.27 to 0.03 and therefore significantly improve the symmetry of the PSF. Simultaneous observations of the PSF in the {optical} ($λ= $ 750 nm, $Δλ=$ 50 nm) show that during these tests we were correcting aberrations common to the optical and NIR paths within SCExAO. Going forward, the algorithm is suitable for incorporation into observing modes, which will enable PSFs of higher quality and stability during science observations.

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