Removing instability noise in nulling interferometers
Removing instability noise in nulling interferometers
复制标题
消除调零干涉仪中的不稳定噪声
DOI：
10.1117/12.670603
复制
发表时间：
2006
期刊：
影响因子：
--
通讯作者：
O. Lay
中科院分区：
文献类型：
--
作者：
O. Lay
美国宇航局的类地行星射电干涉仪（TPF-I）和欧空局的达尔文任务旨在直接探测来自附近恒星周围类地行星的中红外光子。调零干涉测量技术用于抑制来自母星星的光，通常比行星亮107倍，角偏移为10-100质量。有两类噪声：来自恒星泄漏的光子散粒噪声，本地和exo-zodiacal尘埃，以及来自仪器响应变化的不稳定噪声。散粒噪声要求仪器零值深度至少为10-5。不稳定性噪声需要~10-6的零深度，对应于~1 nm rms的光路控制和~0.2%的相对强度控制;这些要求目前推动了仪器的设计。本文介绍了一种新的技术，有效地消除不稳定性噪声的影响。这将调零要求放宽了约10倍，并使行星探测对仪器变化具有鲁棒性。与此同时，探测和表征行星所需的积分周期缩短，阵列的角分辨率显著提高。分析和模拟，并讨论了阵列架构的影响。
The NASA Terrestrial Planet Finder Interferometer (TPF-I) and ESA Darwin missions are designed to directly detect mid-infrared photons from earth-like planets around nearby stars. The technique of nulling interferometry is used to suppress the light from the parent star, typically 107 times brighter than the planet, with an angular offset of 10-100 mas. There are two classes of noise: photon shot noise from the stellar leakage, local- and exo-zodiacal dust, and instability noise from variations in the instrument response. Shot noise requires that the instrument null depth is at least 10-5. The instability noise requires a null depth of ~10-6, corresponding to control of the optical paths at ~1 nm rms, and control of relative intensities at ~0.2%; it is these requirements that currently drive the design of the instrument. This paper describes a new technique that effectively removes the effect of instability noise. This relaxes the nulling requirement by a factor ~10 and makes planet detection robust to instrument variations. At the same time, the integration period needed to detect and characterize planets is reduced and the angular resolution of the array is significantly improved. Analysis and simulations are presented, and implications for the array architecture are discussed.