Self-coherent camera as a focal plane wavefront sensor: simulations
Self-coherent camera as a focal plane wavefront sensor: simulations
复制标题
作为焦平面波前传感器的自相干相机：模拟
DOI：
10.1051/0004-6361/200912902
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
M. Mas
中科院分区：
文献类型：
--
作者：
R. Galicher;P. Baudoz;G. Rousset;J. Totems;M. Mas
直接探测系外行星需要高动态范围成像。日冕仪可能是解决方案，但它们在太空中的性能受到波前误差（光学器件的制造误差、温度变化等）的限制，这些误差会在最终图像中产生准静态恒星散斑。已经提出了几种解决方案来解决这种散斑噪声。差分成像技术在后处理成像中将参考图像减去冠状残留物。其他技术尝试使用可变形镜来主动校正波前误差。在这种情况下，必须在科学图像中以极高的精度测量波前像差。我们提出将自相干相机依次用作焦平面波前传感器，用于主动校正和差分成像。对于这两种用途，恒星散斑在科学图像中进行空间编码，从而最大限度地减少差异像差。该编码基于主恒星与其环境之间的光不相干原理。在本文中，我们首先讨论可变形镜的一个固有局限性。然后，详细研究了自相干相机的几个参数。我们还提出了一种简单而稳健的设计，将自相干相机与使用 Lyot 光阑的日冕仪相关联。最后，我们讨论了与四象限相位掩模关联的情况，并通过数值证明这种设备能够在现实条件下探测类地行星。该技术的参数研究让我们相信，它可以在未来专门用于系外行星直接成像的仪器中非常容易地实现。
Direct detection of exoplanets requires high dynamic range imaging. Coronagraphs could be the solution, but their performance in space is limited by wavefront errors (manufacturing errors on optics, temperature variations, etc.), which create quasi-static stellar speckles in the final image. Several solutions have been suggested for tackling this speckle noise. Differential imaging techniques substract a reference image to the coronagraphic residue in a post-processing imaging. Other techniques attempt to actively correct wavefront errors using a deformable mirror. In that case, wavefront aberrations have to be measured in the science image to extremely high accuracy. We propose the self-coherent camera sequentially used as a focal-plane wavefront sensor for active correction and differential imaging. For both uses, stellar speckles are spatially encoded in the science image so that differential aberrations are strongly minimized. The encoding is based on the principle of light incoherence between the hosting star and its environment. In this paper, we first discuss one intrinsic limitation of deformable mirrors. Then, several parameters of the self-coherent camera are studied in detail. We also propose an easy and robust design to associate the self-coherent camera with a coronagraph that uses a Lyot stop. Finally, we discuss the case of the association with a four-quadrant phase mask and numerically demonstrate that such a device enables the detection of Earth-like planets under realistic conditions. The parametric study of the technique lets us believe it can be implemented quite easily in future instruments dedicated to direct imaging of exoplanets.