论文标题
宽带冠冕式涡旋相位蒙版理论和实验室演示的宽带冠状示例
A Family of Phase Masks For Broadband Coronagraphy Example of the Wrapped Vortex Phase Mask Theory and Laboratory demonstration
论文作者
论文摘要
未来的仪器需要在大光谱范围上有效的冠状动脉绘制，以使宽带成像或频谱表征系外行星1E8比其恒星。提出了几种解决方案。学生apodizer可以通过1E10因子降低恒星强度，但仅传输了行星光的一些易变。相/振幅面具的级联既可以衰减星光并传输大部分行星光线，但是对齐的光学数量并不是仪器的实际解决方案。最后，矢量相掩码可用于检测接近明亮恒星的微弱源，但是它们需要使用高质量的圆极化器，并且对于先前的溶液，这会导致一种具有许多光学器件的复杂仪器以对齐和稳定。我们提出了一个简单的冠状动脉，需要一个标量相掩码和一个二进制lyot停止，仅为行星光（> 50％）提供高传输量（> 50％），并且在大光谱带通道（〜30％）和360度视野上的星光高衰减。从数学考虑上，我们发现了针对未探测的学生进行了优化的2D相掩模的家族。一个面具是方位角包裹的涡旋相位坡道。我们使用数值模拟和实验室测试来探测其冠状性能。从数值模拟中，我们预测包裹的涡流可以在29％带通恒星图像的峰值上降低1E4的峰值，而在18％的带通上，以〜4 lambda/d的速度传播超过50％的行星通量。我们在550nm至870nm之间的可见光中确认实验室中的这些预测。我们还获得了实验室深色孔图像，其中可在3sigma下检测到宿主星通量的3e-8倍。利用一种新技术来蚀刻连续的2D功能，可以轻松地制造出新型的面具，为宽带Coronagraphy开发新的可能性。
Future instruments need efficient coronagraphs over large spectral ranges to enable broadband imaging or spectral characterization of exoplanets 1e8 fainter than their star. Several solutions were proposed. Pupil apodizers can attenuate the star intensity by a 1e10 factor but they transmit a few percents of the planet light only. Cascades of phase/amplitude masks can both attenuate the starlight and transmit most of the planet light but the number of optics to align is not a practical solution for an instrument. Finally, vector phase masks can be used to detect faint sources close to bright stars but they require the use of high quality circular polarizers and as for the previous solution, this leads to a complex instrument with numerous optics to align and stabilize. We propose simple coronagraphs that need one scalar phase mask and one binary Lyot stop only providing high transmission for the planet light (>50%) and high attenuation of the starlight over a large spectral bandpass (~30%) and a 360 degree field-of-view. From mathematical considerations, we find a family of 2D-phase masks optimized for an unobscured pupil. One mask is an azimuthal wrapped vortex phase ramp. We probe its coronagraphic performance using numerical simulations and laboratory tests. From numerical simulations, we predict the wrapped vortex can attenuate the peak of the star image by a factor of 1e4 over a 29% bandpass and 1e5 over a 18% bandpass with transmission of more than 50% of the planet flux at ~4 lambda/D. We confirm these predictions in laboratory in visible light between 550nm and 870nm. We also obtain laboratory dark hole images in which exoplanets with fluxes that are 3e-8 times the host star flux could be detected at 3sigma. Taking advantage of a new technology for etching continuous 2D-functions, new type of masks can be easily manufactured opening new possibilities for broadband coronagraphy.
