摘要
依据500m口径球面射电望远镜(FAST)主动反射面工作原理及相关结构尺寸,基于反射面单元动态面形精度分析研究了FAST瞬时抛物面的拟合精度。首先,以反射面单元为研究对象,自节点开始推导考虑了机构运动的反射面单元动态面形精度计算方法。然后,提取不同区域19块反射面单元的各自9种初始面形工况,给出了分析算例。最后,基于单元动态精度特性,提出瞬时抛物面机械本体拟合精度及考虑馈源照明函数的半光程差拟合精度预估方法,并给出2种改善措施,即扩大可控区至300m抛物面外一层节点靶标,及抛物面周圈节点靶标向球心、中心反向各自偏移4mm。结果表明:反射面单元初始面形应优选面形精度RMS为2mm的波浪式面板。改进控制策略后机械本体拟合精度提高至RMS为3.938mm,优于RMS为5mm的设计指标,此时半光程差拟合精度RMS为0.629mm。该项研究对确定反射面单元初始面形及调节瞬时抛物面拟合精度很有意义。
According to the working principle of the active reflector surface in Five-hundred-meter Aperture Spherical radio Telescope （FAST） and its structure dimension, the fitting accuracy of instantaneous parabolic reflector for the FAST was researched based on analysis of the dynamic surface accuracy of reflector element. Firstly, a reflector element was selected as research object, its calculating formulas taking the mechanism movement into account were deduced from a joint to solve dynamic surface accuracy. Then, by taking 19 reflector elements from different regions for examples, the characteristics under 9 initial surface types were analyzed correspondingly. Finally, based on the dynamic characteristics of reflector element, the fitting accuracy estimation methods of instantaneous parabolic surface were proposed, including mechanical surface precision and semi-optical path difference surface accuracy with feeding lighting function. Furthermore, two improved measures for surface accuracy were given, and they were enlarging joint controlling area to next joint target ring of parabolic surface border, and offsetting the outer ring joint targets by 4 mm to the sphere center and also moving center targets by 4 mm to reserve direction. Results demonstrate that the panel with surface accuracy RMS 2 mm is a preferential selection for initial surface type of reflector element. After changing control strategy, the mechanical surface accuracy increases to RMS 3. 938 mm, better than the index RMS 5 mm, Meanwhile, the semi-optical path difference surface accuracy reaches to RMS 0. 629 mm. This research has important significance for ensuring reflector element initial surface type and adjusting fitting accuracy of the instantaneous parabolic reflector.
出处
《光学精密工程》
EI
CAS
CSCD
北大核心
2015年第7期2051-2059,共9页
Optics and Precision Engineering
基金
国家自然科学基金资助项目(No.11173035)
关键词
500m口径球面射电望远镜
反射面单元
初始面形
动态面形
面形精度
瞬时抛物面
拟合精度
Five-hundred-meter Aperture Spherical radio Telescope（FAST）
reflector element
initial surface
dynamic surface
surface accuraey
instantaneous parabolic reflector
fitting accuracy
作者简介
薛建兴（1982-），男，天津人，硕士，工程师，2007年于北京理工大学获得硕士学位，主要从事天文技术与方法、机械设计及理论、虚拟样机仿真分析等方面的研究。E-mail：jxxue@bao．ac．cn
古学东（1964-），男，河北沧州人，硕士，高级工程师，1989年于北京科技大学获得硕士学位，主要从事天文仪器、机械结构的设计、分析及研究。E—mail：xdgu@nao．cas．cn
王启明（1961-），男，辽宁沈阳人，博士，研究员，2000年于东北大学获得博士学位，2002年为清华大学博士后，主要从事天文技术与方法、机械制造、串并联机器人、机械结构动态特性分析等方面的研究。E-mail：qmwang@bao．ac．cn
