高精度离轴非球面主动应力加工技术研究

On the demand of the construction of the next generation of super-large astronomical telescope, the technology of the active stress processing becomes a hot issue once again during the research of optical manufacturing. This technology that has a high rate for the removed material still can only be used as a means of grinding polishing stage because of the limitation of the machining accuracy. This project achieves a high efficiency and high precision manufacturing for the off-axis aspheric of surface of which the diameter is more than one meter on the base of the research of the error analysis of high precision off-axis aspheric surface active stress processing technology as well as solving accuracy problems in active stress processing technology development. First of all, the sources of the errors that affect the machining accuracy of active stress are analyzed, and then there kinds of main errors are researched respectively, such as the error of the mirror surface deformation, the error of the processing and the error produced by the adhesive shrinkage stress release of spring back, correspondingly, and the solutions are also put forward. Finally, the experiment of the active stress processing is carried out, and the effectiveness of the proposed scheme is verified. This achievement will have a very positive and important effect to improve the ability of the manufacture the astronomical telescope system with a very large diameter.

在新一代超大型天文望远镜建设需求的推动下，主动应力加工技术再次成为光学制造领域研究的热点问题。尽管具有极高的材料去除效率，但是受到加工精度限制，目前，主动应力加工技术仍然只能作为粗抛光手段使用。针对这一问题，本项目提出开展以误差分析为切入点的高精度离轴非球面主动应力加工技术研究，旨在解决困扰主动应力加工技术发展的精度问题，为实现1m量级离轴非球面的高效率、高精度制造提供必要的理论依据的实验数据。首先对影响主动应力加工精度的误差来源进行分析，然后分别对三种主要误差——镜面变形误差、加工过程误差以及由胶黏剂收缩应力释放所产生的回弹误差——的处理方法进行研究，提出相应的解决方案，最后开展主动应力加工实验，对方案的有效性进行验证。此项目的开展，对于提高我国超大型天文望远镜系统的研制能力将产生一定的积极作用。

在新一代超大型天文望远镜建设需求的推动下，主动应力加工技术再次成为光学制造领域研究的热点问题。尽管具有极高的材料去除效率，但是受到加工精度限制，目前，主动应力加工技术仍然只能作为粗抛光手段使用。本项目在对主动应力抛光技术加工过程误差来源进行分析的基础上，开展了包括薄镜面高精度主动变形控制理论、主动应力加载装置结构设计和薄镜面主动应力抛光实验三方面研究工作。提出了一种基于结构模式的面形校正力算法，该算法对Zernike低阶像差具有良好的校正效果；设计一套用于Φ324mm口径弯月薄镜的6+1点底面驱动主动应力抛光支撑系统，力促动器的输出范围大于±50N，力分辨率为10mN；对支撑系统变形精度进行了测试，变形误差PV<0.3um，约为总变形量的6%；以结构模式中像散项为校正目标（PV=19.46um，RMS=4.71um）开展应力抛光实验，变形去除精度达到PV=0.22um，RMS=0.05um。项目研究成果将为后续开展1m量级离轴非球面应力抛光研究提供了一定的理论依据和实验数据，同时本项目中提出的校正力算法和力促动器也适用于主动支撑技术等相关技术。