基于扇形子镜的12m光学红外望远镜拼接共相误差仿真分析

Simulation and Analysis of Co-phasing Errors of the Segmented Primary Mirror Tiled by Petal-shaped Segments in LOT

为满足国内对应用大型通用光学望远镜在光学红外波段进行天文观测的需求,中国计划建设一架12 m大口径光学红外望远镜(12-meter large aperture optical-infrared telescope,LOT).LOT对于中国天文界具有极其重要的意义,将会在近红外波段实现共相.LOT的主镜将采用子镜拼接的方案,由72块扇形子镜拼接而成,并且中央部分有一块直径4.5m的圆形镜.分析了采用扇形子镜拼接方案下LOT的共相误差,提供了详细的共相误差理论推导过程,并对包括3种子镜面外误差在内的误差源进行深入的单独模拟和综合模拟.在共相波长为1μm的条件下,当服从正态分布的倾斜误差的均方根值小于0.016″或服从正态分布的活塞误差的均方根值小于42.5nm时,LOT的斯特列尔比大于0.8.仿真结果对于采用共相拼接镜面主动光学的主镜在LOT中的应用具有重要意义.

In order to fulfill the requirement for astronomical observation in the opticalinfrared band using large universal aperture optical telescopes,China is planning to construct a 12-meter large aperture optical-infrared telescope(LOT).LOT is of particular significance to Chinese astronomy and would be co-phased in the near-infrared waveband.The primary mirror of LOT will be constructed from either hexagonal segments or petal-shaped segments.Analysis of co-phasing errors using a segmented primary mirror tiled by petal-shaped segments for LOT has been presented.The proposed primary mirror of LOT has 72 petal-shaped segments and a 4.5-meter circular mirror in the center.Detailed theoretical derivation of co-phasing errors and simulation about out-plane errors separately and comprehensively have been provided.SR(Strehl Ratio)of LOT is greater than 0.8 when the RMS(Root Mean Square)value of normally distributed tip-tilt errors is less than 0.016′′or the RMS value of normally distributed piston error is less than 42.5 nm at the co-phasing wavelength 1µm.The simulation results are of great importance for the segmented primary mirror with active optics in LOT.