Speckle temporal stability in XAO coronagraphic images
Speckle temporal stability in XAO coronagraphic images
复制标题
XAO 冠状图像中的散斑时间稳定性
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
M. Kasper
中科院分区：
文献类型：
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作者：
P. Martinez;C. Loose;E. A. Carpentier;M. Kasper
上下文限制高对比度成像的噪声的主要来源是由准静态散斑引起的。散斑噪声来源于各种独立光源引起的波前误差，并根据其性质在不同的时间尺度上演化。了解准静态散斑是如何由仪器误差引起的，对于寻找暗淡的恒星同伴至关重要。仪器散斑平均形成一个固定的图案，可以在一定程度上校准，但它们的时间演化最终限制了这种可能性。目标。本研究着重于准静态钉扎散斑现象的实验室证据和表征。具体来说，我们研究的相干放大的静态散斑的贡献，在科学图像中的噪声方差，通过其与准静态散斑的相互作用。方法.在实验室中记录的自适应校正的coronagraphic图像的时间序列的分析，使得在直接和差分coronagraphic图像中的残留散斑图案的时间稳定性的表征。结果我们估计，破坏和快速发展的准静态散斑存在于系统中的埃/纳米级影响静态散斑噪声的稳定性，在最终的图像后，电晕放电。准静态波前误差的时间演化呈现线性幂律，该线性幂律可用于一阶模型来模拟高对比度成像仪器中的准静态散斑演化。
Context. The major source of noise limiting high-contrast imaging is caused by quasi-static speckles. Speckle noise originates from wavefront errors caused by various independent sources, and evolves on different timescales depending on their nature. An understanding of how quasi-static speckles originate from instrumental errors is paramount to the search for faint stellar companions. Instrumental speckles average to form a fixed pattern, which can be calibrated to a certain extent, but their temporal evolution ultimately limits this possibility. Aims. This study focuses on the laboratory evidence and characterization of the quasi-static pinned speckle phenomenon. Specifically, we examine the coherent amplification of the static speckle contribution to the noise variance in the scientific image, through its interaction with quasi-static speckles. Methods. The analysis of a time series of adaptively corrected, coronagraphic images recorded in the laboratory enables the characterization of the temporal stability of the residual speckle pattern in both direct and differential coronagraphic images. Results. We estimate that spoiled and rapidly evolving quasi-static speckles present in the system at the angstrom/nanometer level affect the stability of the static speckle noise in the final image after the coronagraph. The temporal evolution of the quasi-static wavefront error exhibits a linear power law, which can be used to first order to model quasi-static speckle evolution in high-contrast imaging instruments.