大型干涉仪镜子的支承设计与温度变形分析

Support Schemes and Thermal Deformation Analysis of Large-Aperture Interferometer Mirrors

在星间激光通信中,涉及对大口径衍射极限激光波面的检测,为保证测量精度,必须严格控制波面干涉仪镜子的自重和温度变形。采用有限元方法对大型干涉仪镜子在不同支承方式下的表面变形进行了分析,结果表明,接触角为180°的钢带支承是较好的支承方式,反射镜表面变形峰谷(PV)值仅为1.35nm,均方根(RMS)值为0.363nm。根据这一结论,设计了一个固定支承点与浮动支承相结合的超静定钢带支承结构。在该结构下,分析了镜子轴向、径向、周向的温度梯度效应,分析数据表明,镜子的热弹性变形远大于自重变形,建议采取一定的温控措施,并采用平均效应的方法降低热效应的影响。

In the field of inter-satellite communication, the measurement of large-aperture and diffraction limit wavefront is required. In order to ensure the measuring precision, the deformations of the interferometer mirrors induced by self-weight and the thermal effects must be controlled strictly. In a variety of support schemes, the surface deformations of large-aperture interferometer mirrors are computed by means of finite element method. By comparison, the band support of 180° wrap angle is accepted to be optimum. In that case, the peak-to-valley (P-V) value is only 1.35 nm and RMS value is 0.363 nm. According to the results, the statically indeterminate supporting structure is designed. In that mounting configuration, the thermoelastic analysis for the mirror is performed for special thermal effects (axial, radial, circumferential temperature gradients). According to the results, it is clear that the influence of thermal gradient effects is much greater than the ones of self-weight. Lastly, some suggestions (relative constant temperature circumstance and average processing) are given to reduce the influence of thermal effects.