Speckle Symmetry with High‐Contrast Coronagraphs
Speckle Symmetry with High‐Contrast Coronagraphs
复制标题
高对比度日冕仪的散斑对称性
DOI：
10.1086/338914
复制
发表时间：
2002
影响因子：
3.5
通讯作者：
D. Rouan
中科院分区：
文献类型：
--
作者：
Anthony Boccaletti;P. Riaud;D. Rouan
我们研究了用高对比度日冕成像仪和极端自适应光学系统获得的残余散斑的图案。特别是，我们提供了对称性的证据，对于非常小的相位缺陷，仅取决于冠照仪衰减瞳孔衍射图的能力。在这种情况下，图像的中心对称减法显著提高了信噪比。在某些特殊情况下，探测到明亮恒星周围的非常微弱的伴星可能会受益于这一特性。数值模拟表明，当使用四象限相位掩模日冕仪时，对于很高的Strehl比(SR>；0.96)和填充的圆形孔径，出现了散斑对称性。
We investigate the pattern of residual speckles obtained with high‐contrast coronagraphs and extreme adaptive optics systems. In particular, we provide evidence of symmetry occurring for very small phase defects depending only on the ability of the coronagraph to attenuate the pupil diffraction pattern. In such a case, a centrosymmetrical subtraction of the image significantly increases the signal‐to‐noise ratio. Detection of very faint companions around bright stars may benefit from this characteristic in some particular conditions. Numerical simulations show that speckle symmetry takes place when using a four‐quadrant phase mask coronagraph, for very high Strehl ratio (SR>0.96) and with a filled circular aperture.