巨型科学可控反射镜缩比模型系统抖动检测

Jitter measurement of giant steerable science mirror prototype

为了更好地对三十米望远镜三镜,即巨型科学可控反射镜(Giant Steerable Science Mirror,GSSM)的抖动(Jitter)特性进行研究,利用信号的复数表达分别分析了时域积分与频域积分的特性,明晰了二者之间的关系,并从积分精度的角度上,选择频域积分作为GSSM Jitter数据的处理方法。同时,对比了高精度编码器以及高精度加速度计对抖动测量的适用性,验证了使用加速度计测量的合理性。针对GSSM内部振动的影响,选择频响函数法测量内部作用力。最后,对GSSM缩比模型进行了Jitter检测,得到镜面方向Jitter为0.079 7μm,方位轴方向为14.143 2 mas,俯仰轴方向为20.747 5mas,内部作用力为0.003 3N。

The Giant Steerable Science Mirror （GSSM） is the tertiary mirror of the future large telescope, Thirty Meter Telescope. The characteristics of jitter were analyzed in the time domain and frequency domain, including the relationship between them. By considering the integral precision, frequency domain integration was chosen as the GSSM dithering data processing method. Simultaneously, the applicability of a high-precision encoder and high precision accelerometer for jitter measurement was compared, and the rationality of using the accelerometer was verified. For the internal vibration of the system, the internal forces were measured by the method of Frequency Response Function. Using the above findings, the jitter detection of the GSSM prototype was carried out. The jitter in the mirror is 0.079 7 μm, around the azimuth axis is 14.143 2 mas, around the tilt axis is 20.747 5 mas, and the internal force was 0.003 3 N.