甚大望远镜上的HARMONI：用于微米级指向精度的LPOU校准
HARMONI at ELT: LPOU calibrations for a micron-level pointing accuracy
AI总结：
研究HARMONI在甚大望远镜上为达微米级指向精度的校准问题，核心方法是探讨靠近引导探头插入校准掩膜及添加重新聚焦光学元件的可能性，主要贡献是分析其不同变体对图像质量及定位误差分辨能力的影响并经模拟验证。
AI中文摘要：
HARMONI是甚大望远镜的首台自适应光学辅助近红外积分场光谱仪。它覆盖800纳米至2450纳米光谱范围，分辨率3000至7000，空间采样为25毫角秒和6毫角秒，可在SCAO和MCAO两种自适应光学模式下运行。项目在2025年重新规划设计阶段后进入最终设计阶段。为实现最佳图像质量，HARMONI需通过三个引导探头进行指向误差测量。每个引导探头是带有肩肘平台的机械臂，光学上等效于两个连接在一起的潜望镜。由于肩肘电机的任何系统定位误差都会导致指向误差测量误差，所以需要合适的几何校准参考。以往设计中校准参考是可部署在校准掩膜，插入望远镜焦平面，但这种方法阻碍引导传感器区分电机贡献和仪器光学其他效应。本文探讨将校准掩膜尽可能靠近引导探头插入的可能性，以及在引导传感器光路中添加必要的重新聚焦光学元件。讨论了该想法的不同变体、对图像质量的影响以及分辨小于1微米定位误差的能力。通过RayZaler中的光学模拟对这些分析结果进行交叉验证，并用于确定该设计可实现的预期校准精度范围。
英文摘要：
HARMONI is the first light, adaptive optics assisted, near-IR integral field spectrograph for the ELT [1]. It covers a spectral range from 800 nm to 2450 nm with resolving powers from 3000 to 7000 and spatial sampling of 25 mas and 6mas. It can operate in two adaptive optics modes, SCAO (including a high contrast capability) and MCAO. The project is resuming its final design phase after a rescope design phase in 2025. To achieve its optimal image quality, HARMONI needs to perform pointing error measurement by means of three guide probes. Each guide probe is a robotic arm with a shoulder-elbow stage that is optically equivalent to two periscopes connected together. Since any systematic positioning error of the shoulder-elbow motors will result in a measurement error of the pointing error itself, an appropriate geometric calibration reference is necessary. In previous designs, this calibration reference took the form of a deployable calibration mask that could be inserted in the telescope's focal plane. However, this approach prevents the guiding sensors from distinguishing motor contributions from other effects caused by the instrument optics. In this work, we explore the possibility of inserting the calibration mask as close to the guide probes as possible, along with the addition of the necessary refocus optics in the light path of the guiding sensors. We discuss different variations of this idea, their effect on the image quality, and their ability to resolve positioning errors smaller than 1 μm. The results of these analyses were cross-validated by means of optical simulations in RayZaler, and will be used to put bounds to the expected calibration accuracy achievable by this design.
