基于多波束接收系统的大型射电望远镜主动反射面面形的实时测量技术研究

The large radio telescopes have advantages in high sensitivity and high resolution, and they play a major role in astronomical research and deep-space exploration. Affected by gravity, thermal, wind, and other factors, the main surfaces of the large radio telescopes have dynamic deformation which affects electrical performance of the telescopes, so most of the telescopes adopt active reflector technique to modify the dynamic deformation. The real-time measurement for the surface shape of the active reflector is a core technical problem which makes the active reflector work in high efficiency. Based on the multiple-beam receiving system, the project relies on the Tian Ma telescope, and adopts the phase-retrieval holography to implement the real-time measurement technology for the surface shape of the active reflector. The specific contents are as follows. Firstly, the phase-retrieval algorithm is researched based on one on-focus pattern and one out-focus pattern, and the algorithm precision is evaluated on different situations. Secondly, the fast and high-accuracy pattern measurement method and data processing technique are researched based on the multiple-beam receiving system and daisy-pattern scanning mode. Thirdly, based on the above two techniques, a measurement system is established, and the accuracy, repeatability, and measurement precision of the whole system are measured and analyzed. The project can realize the real-time measurement for the surface shape of the large radio telescope active reflector, and is of great value in improving the application ability of active reflector for the large telescopes.

大型射电望远镜具有高灵敏度和高分辨率的优势，在天文研究和深空探测中发挥着重要作用。但是受重力、温度和风等因素的影响，大型射电望远镜主反射面会发生动态形变，从而影响其电性能，为此大型射电望远镜大多采用主动反射面以修正动态形变，其中主动反射面面形的实时测量是主动反射面高效率工作的核心技术难题。本项目依托天马望远镜，基于多波束接收系统，采用相位恢复全息测量技术，实现主动反射面面形的实时测量技术。研究内容包括：基于单幅聚焦和单幅离焦天线方向图，研究快速、高精度口径面相位提取算法，并评估不同情况下的算法精度；基于多波束接收系统和花瓣扫描模式，研究快速、高精度天线方向图的测量和数据处理技术；基于上述两项技术，建立测量系统，并对整套测量系统的准确性、重复性和测量精度等进行实测和分析。本项目的成功实施可实现大型射电望远镜主动反射面面形的实时测量，对于提高大型射电望远镜对于主动反射面的应用能力具有重要价值。

大型射电望远镜具有高灵敏度和高分辨率的优势，在天文研究和深空探测中发挥着重要作用。但是受重力、温度等因素的影响，大型射电望远镜主反射面会发生动态形变，从而影响其电性能，为此大型射电望远镜采用主动反射面以修正动态形变，其中主动反射面面形的实时测量是主动反射面高效率工作的核心技术难题。本项目依托天马望远镜，基于多波束接收系统，采用相位恢复全息测量技术，实现主动反射面面形的实时测量技术。主要研究内容包括：基于单幅聚焦和两幅离焦天线方向图，研究快速、高精度口径面相位提取算法，并评估了不同情况下的算法精度；基于多波束接收系统，研究了快速、高精度天线方向图的测量和数据处理技术，经过实测每副图的测量时间小于2.3分钟，一次测量的总时间小于8分钟。准确测量得到了大型射电望远镜的重力形变和温度形变，测量精度可达70微米。本项目的成功实施实现了大型射电望远镜主动反射面面形的实时测量，对于提高大型射电望远镜对于主动反射面的应用能力具有重要价值。