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arXiv 1104.1934astro-ph.IM
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用于VLTI新一代仪器的优化条纹传感器

Optimized fringe sensors for the VLTI next generation instruments

N. Blind, O. Absil, J. -B. Lebouquin, J. -P. Berger, A. Chelli

摘要:

上下文随着下一代地基成像干涉仪的到来,同时结合4到可能6个望远镜,也强烈需要新一代的条纹跟踪器能够同相这种阵列。这些仪器必须非常灵敏,并在迅速变化的观测条件下提供可靠的操作。目标。我们的目标是确定最佳的特点条纹传感器的概念与4或6望远镜。目前的检测器的限制迫使我们考虑同轴成对组合方案的基础上的解决方案。方法.我们独立研究了条纹传感过程的几个方面:1)如何测量相位和群延迟,以及2)如何组合望远镜,以确保在真实条件下精确和鲁棒的条纹跟踪。得益于分析开发和数值模拟,我们定义了最佳条纹传感器概念,并使用我们专用的端到端仿真工具sim2GFT计算了4望远镜的预期性能。结果我们首先表明,通过在几个步骤中获得的数据(即通过时间调制的光程差)测量的相位和群延迟是非常敏感的大气湍流,因此得出结论,它是更好地获得条纹位置与一组数据同时获得。随后,我们表明,在所有同轴成对计划,适度冗余的概念增加的灵敏度以及在各种大气或观测条件下的鲁棒性。合并所有这些结果,端到端的模拟表明,我们的4望远镜条纹传感器的概念是能够跟踪条纹至少90%的时间达到7.5和9.5的限制幅度分别为1.8和8.2米VLTI望远镜。

英文摘要:

Context. With the arrival of the next generation of ground-based imaging interferometers combining from 4 to possibly 6 telescopes simultaneously, there is also a strong need for a new generation of fringe trackers able to cophase such arrays. These instruments have to be very sensitive and to provide robust operations in quickly varying observational conditions. Aims. We aim at defining the optimal characteristics of fringe sensor concepts operating with 4 or 6 telescopes. The current detector limitations impose us to consider solutions based on co-axial pairwise combination schemes. Methods. We independently study several aspects of the fringe sensing process: 1) how to measure the phase and the group delay, and 2) how to combine the telescopes in order to ensure a precise and robust fringe tracking in real conditions. Thanks to analytical developments and numerical simulations, we define the optimal fringe-sensor concepts and compute the expected performance of the 4-telescope one with our dedicated end-to-end simulation tool sim2GFT. Results. We first show that measuring the phase and the group delay by obtaining the data in several steps (i.e. by temporally modulating the optical path difference) is extremely sensitive to atmospheric turbulence and therefore conclude that it is better to obtain the fringe position with a set of data obtained simultaneously. Subsequently, we show that among all co-axial pairwise schemes, moderately redundant concepts increase the sensitivity as well as the robustness in various atmospheric or observing conditions. Merging all these results, end-to-end simulations show that our 4-telescope fringe sensor concept is able to track fringes at least 90% of the time up to limiting magnitudes of 7.5 and 9.5 for the 1.8- and 8.2-meter VLTI telescopes respectively.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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