用于REDSoX软X射线偏振计中透射光栅精密对准的激光计量技术
Laser Metrology for Precision Alignment of Transmission Gratings in the REDSoX Soft X-ray Polarimeter
AI总结：
本研究针对REDSoX软X射线偏振计的48个透射光栅对准需求，改进激光反射计量技术，通过原型验证实现优于容差要求的对准精度，为相关仪器光栅装配提供可扩展方法。
AI中文摘要：
软X射线偏振计火箭演示实验（REDSoX）是NASA的探空火箭任务，旨在完成0.2-0.4 keV能段的首次天体光谱偏振测量。该仪器采用临界角透射（CAT）光栅将入射X射线色散到横向渐变多层膜（LGML）反射镜上，要求48个独立光栅在偏航、俯仰和滚转方向上的对准精度达到6角分以内。为支持光栅阵列的系统装配，我们改进了扫描激光反射计量技术，通过三个位置敏感探测器（PSD）测量法向反射、斜反射以及衍射的紫外激光束，利用测量到的光束位置变化重构每个光栅的局部偏航、俯仰和滚转角度，为机械调整提供实时反馈。我们使用包含两个光栅的微型光栅结构原型对该系统进行验证，对准完成后，组件经历了飞行级随机振动测试和鉴定级正弦扫描。测试前后的测量结果显示，光栅的相对姿态保持在1角分以内，小于REDSoX对准容差的17%。本研究为REDSoX及未来X射线光谱仪器的大型透射光栅阵列装配与验证建立了可重复且可扩展的方法。
英文摘要：
The Rocket Experiment Demonstration of a Soft X-ray Polarimeter (REDSoX) is a NASA sounding-rocket mission designed to perform the first astrophysical spectropolarimetry in the 0.2-0.4 keV energy band. The instrument uses critical-angle transmission (CAT) gratings to disperse incident X-rays onto laterally graded multilayer (LGML) mirrors, requiring 48 individual gratings to be co-aligned to within 6 arcminutes in yaw, pitch, and roll. To support the systematic assembly of the grating array, we adapted a scanning laser-reflection metrology technique in which normal-reflected, angled-reflected, and diffracted ultraviolet laser beams are measured using three position-sensitive detectors (PSDs). Changes in the measured beam positions are used to reconstruct the local yaw, pitch, and roll of each grating and provide real-time feedback during mechanical adjustment. We demonstrate the system using a prototype miniature grating structure containing two gratings. Following co-alignment, the assembly underwent a flight-level random-vibration test followed by a qualification-level sine sweep. Measurements obtained before and after testing showed that the relative grating orientations were retained to within 1 arcminute, less than 17% of the REDSoX co-alignment tolerance. This work establishes a reproducible and scalable approach to the assembly and verification of large transmission-grating arrays for REDSoX and future X-ray spectroscopic instruments.
