温度和支撑方式对1.2 m SiC主镜面形的影响分析

为了研究温度和支撑方式对大口径SiC主镜用于地基望远镜的影响,基于1.2 m SiC主镜建立了有限元模型,分析了主镜在被动支撑和自由膨胀时,恒定温度场,轴向温度梯度,径向温度梯度和内外温差等对主镜面形的影响.结果表明,存在温度梯度时,支撑方式影响不明显,无论是被动支撑还是自由膨胀,镜面面形均很大.在达到热平衡后,即稳态温度场下,支撑方式的影响明显,只有在主镜自由膨胀时,温度对主镜面形的影响比较小,镜面的RMS<0.02 nm/℃.因此如果主镜采用柔性支撑或浮动支撑方式,大口径SiC主镜可以应用在地基望远镜中.

Study on the Influence of Temperature and Support Style to the 1.2m Sic Primary Mirror Surface Figure

 A 1.2 m SiC primary mirror FEA model was built to analyze temperature and support style effects on the large aperture SiC primary mirror,which was applied to the ground based on telescope.With the primary mirror in passive support and free expansion,influences of steady state temperature field,axial direction temperature gradient,radial direction temperature gradient,and internal-external temperature gradient to primary mirror surface figure were analyzed.The result indicates that the influences of the support style are not obvious,whether passive support or free expansion,and the primary mirror surface figure is big with temperature gradient.When achieving heat balance,the influence of the support style is obvious only when the primary mirror free expand,and the temperature influence is small,surface figure RMS<0.02nm/℃.If the primary mirror adopts flexibility or floating support style,the large aperture SiC primary mirror can be applied to the ground based telescope.