大口径望远镜四通垂直度检测方法研究

Study on verticality measurement of center block in large telescope

为了保证大口径望远镜俯仰轴系的回转精度,对四通轴孔同轴度及轴孔轴线与两端面的垂直度等误差提出了很高的加工检测要求。针对大口径光学望远镜四通结构件的形位误差检测需求,并根据四通的结构特点,首先,提出了运用测微准直望远镜配合自准直仪等光学测量设备进行四通件的形位误差检测的方案。本方案利用测微望远镜光轴模拟四通轴孔的轴线,用精密侧角的自准直仪来测量四通端面与轴孔轴线之间的偏角,通过对测量数据进行处理计算即可得到被测件的垂直度。之后,对该方法的基本测量原理进行研究分析,并结合一套四通模拟件进行了垂直度的测量。通过实验验证了该检测方案的可行性,获得了精确的测量数据,测得其垂直度为98.2″,重复性RMS值为2.3″。最后,并对本测量方法的测量不确定度进行了分析,其合成标准不确定度为2.2″。本文所提出方法可以满足大口径望远镜四通形位误差的检测需求,对大型轴孔类结构件的形位误差检测具有一定的借鉴意义。

In order to ensure the rotation precision of the tilt axis assembling in large telescope,very high form and position precision in manufacture and measurement is needed,especially for the coaxiality of the shaft holes in the center block and the verticality of the axis to the two end faces of the shaft holes. According to the form and position error requirement of center block in the large aperture telescope and its structural features,micro alignment telescope cooperated with the auto-collimator is used to measure the form and position error of the center block. The optical axis of micro alignment telescope is regarded as the axis of the holes in center block,and the auto-collimator is used to measure the angular deviation between the end face and the axis of the hole. Furthermore,the verticality of the measured piece is obtained by processing the measuring data. The basic principle of this method is analyzed,a simulator verticality of center block is measured. The verticality of the axis is 98. 2″,and the RMS is 2. 3″. The synthetic standard uncertainty is 2. 2″. The proposed method meets the form and position error requirement of center block in the large aperture telescope,and has certain reference significance for form and position error measurement of similar large structures.