AI 中文总结
GRAVITY+项目通过改进光纤耦合器的高精度反射镜，降低非共光路像差，有望将GRAVITY的天体测量精度从30-100微角秒提升至亚10微角秒。
AI 中文摘要
GRAVITY是近红外天体测量干涉测量领域的先进仪器，其相位参考双场模式通常可达到30-100微角秒的天体测量精度，但尚未达到其基本极限，仍有多个因素可实现改进。本文聚焦于系统误差的影响，尤其是GRAVITY光纤耦合器中科学通道与计量信号之间的非共光路像差的影响。通过使用专用光纤耦合器复制品和1908纳米的相移干涉测量进行全面的实验室测量，我们在实验室中以纳米级精度表征了这些高阶波前误差。我们还通过对双星系统GJ65的观测，在天空上表征了这些高阶波前缺陷对小角天体测量的影响。作为GRAVITY+项目的一部分，专为纳米级表面质量设计的高精度反射镜（相比现有GRAVITY注入光学器件提升一个数量级）目前正在生产中，预计将于2027年底前安装到光纤耦合器单元中。此次升级有望在双场模式下，仅需几分钟的积分时间即可实现亚10微角秒级的天体测量精度。
英文摘要
GRAVITY is a state-of-the-art instrument for near-infrared astrometric interferometry that routinely achieves astrometric accuracy of 30-100 microarcsecond in its phase-referenced dual-field mode. However, its fundamental limit is not yet reached, and can still be improved by several factors. In this paper, we focus on the effect of systematics, and in particular the effect of non-common path aberrations between the science channel and the metrology signal in the GRAVITY Fiber Coupler. Through comprehensive laboratory measurements using a dedicated fiber coupler replica and phase-shifting interferometry at 1908 nm, we have characterized these high-order wavefront errors with nanometer precision in the laboratory. We characterized on-sky the effect of these high-order wavefront imperfections on narrow-angle astrometry, using observations of the binary system GJ65. As part of the GRAVITY+ project, high-precision mirrors designed for nanometer-level surface quality, bringing an order of magnitude improvement over existing GRAVITY injection optics, are currently in production and will be installed in the fiber coupler units by the end of 2027. This upgrade is expected to enable astrometric accuracy at the sub-10 microarcsecond level in dual-field mode with integration times of just a few minutes.
