Design, fabrication, and testing of stellar coronagraphs for exoplanet imaging
Design, fabrication, and testing of stellar coronagraphs for exoplanet imaging
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用于系外行星成像的恒星日冕仪的设计、制造和测试
DOI：
10.1117/12.2273558
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发表时间：
2017
期刊：
影响因子：
--
通讯作者：
Ward Karen
中科院分区：
文献类型：
--
作者：
Knight Justin M.;Brewer John;Hamilton Ryan;Guyon Olivier;Milster Thomas D.;Ward Karen
复杂掩模日冕仪破坏性地干扰不需要的星光，使其能够直接成像系外行星。这是使用焦平面掩模（FPM）完成的; FPM可以是一个简单的掩模，或者在复杂掩模的情况下，是一个多区域的设备，旨在相移多个波长的星光，以创建一个深消色差的恒星点扩散函数零。制造这些掩模需要微加工技术，但许多这样的方法在这方面仍然很大程度上未被探索。我们探索了相位诱导振幅切趾复合掩模冠状放大器（PIAACMC）的复合FPM的制造方法。PIAACMC以前的FPM制造工作集中在掩模可制造性上，同时建模科学产量，以及评估宽带波长操作。此外，目前的制造努力集中在评估电晕放电性能给出了一个单一的方法。我们提出了FPMs制作使用几种工艺路径，包括深反应离子刻蚀和聚焦离子束刻蚀使用硅基板。掩模特征的特征尺寸为5μm，深度范围超过1μm。使用光学干涉仪和扫描电子显微镜表征掩模的制造质量。最初的测试是在斯巴鲁极端自适应光学测试平台上进行的，为未来的实验提供了一个基线，以确定和改善制造公差范围内的电晕放电性能。
Complex-mask coronagraphs destructively interfere unwanted starlight with itself to enable direct imaging of exoplanets. This is accomplished using a focal plane mask (FPM); a FPM can be a simple occulter mask, or in the case of a complex-mask, is a multi-zoned device designed to phase-shift starlight over multiple wavelengths to create a deep achromatic null in the stellar point spread function. Creating these masks requires microfabrication techniques, yet many such methods remain largely unexplored in this context. We explore methods of fabrication of complex FPMs for a Phased-Induced Amplitude Apodization Complex-Mask Coronagraph (PIAACMC). Previous FPM fabrication efforts for PIAACMC have concentrated on mask manufacturability while modeling science yield, as well as assessing broadband wavelength operation. Moreover current fabrication efforts are concentrated on assessing coronagraph performance given a single approach. We present FPMs fabricated using several process paths, including deep reactive ion etching and focused ion beam etching using a silicon substrate. The characteristic size of the mask features is 5μm with depths ranging over 1μm. The masks are characterized for manufacturing quality using an optical interferometer and a scanning electron microscope. Initial testing is performed at the Subaru Extreme Adaptive Optics testbed, providing a baseline for future experiments to determine and improve coronagraph performance within fabrication tolerances.