大型射电望远镜重力模型构建关键技术研究

Large radio telescopes are important tools for radio astronomy research and deep space exploration. Radio telescope performance affects the quality and accuracy of astronomical observations directly. This research proposal will break the traditional measurement method and concentrate on the topic of radio telescope’s gravity model construction with focusing on three type models’ establishment and performance verification: 1) main surface gravity model construction based on microwave holography; 2) sub-reflector gravity model construction based on radio sources and optical method; 3)high precision antenna pointing errors detection and pointing model reformation. To verify the models accurately, beam correction parameters will be applied to improve the measurement accuracy of antenna efficiency. Active surface and sub-reflector six-bar mechanism will also be applied to verify the correctness of the models. A unified measurement platform will be established by using radio source mainly and optical method auxiliarily. This research project will result in the enhancement of the ability in radio telescope models' construction and calibration in theory and practice that will improve the performance of domestic large radio telescopes to better serve the radio astronomy research and deep space exploration.

大型射电望远镜是开展射电天文学和深空探测研究的重要工具，射电望远镜性能直接影响天文观测的质量和测量精度。本研究申请将突破传统测量法，主要围绕实测构建大型射电望远镜主副面重力模型这一主题，重点研究三种模型的构建方法并验证模型的性能：1）研究基于微波全息法实测构建天线主面重力模型；2）研究基于射电和光学法测量副面重力模型；3）研究高精度指向误差检测方法及指向模型改进方法。通过提取天线波束修正参数，提高天线效率测量精度，并启动主动面和副面六杆机构精确验证模型调整的准确性。测量过程主要采用射电法，辅助光学法，建立统一的测量平台。通过本项研究工作，可以确立新型的射电望远镜重力模型测量方法；提高国内射电望远镜测量校正的理论水平和实践能力，改善国内大型射电望远镜的性能，更好地服务于射电天文学和深空探测研究。

通过本项目研究，首先以卫星射电全息法测量并构建天马65米天线最佳俯仰角52度上主面模型，使得面形误差控制到0.3mm（RMS）以内。然后采用VLBI法测量65米天线主面各俯仰角的重力变形，进而构建重力模型，并与仿真结果进行了比较，在此方法实现过程中，除了获得天马65米射电望远镜主面高低俯仰重力模型外，通过口径面相位信息，还成功解算了副面位姿变化情况，与传统幅度扫描法获得的结果一致，这为诊断射电望远镜的副面位姿提供了新的方法。成功采用了PSD方法测量副面横偏，建立了转换矩阵进行校准，测量结果和传统幅度扫描法结果一致，这为射电望远镜建设初期快速构建副面模型提供了方法。