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30 m望远镜三镜是世界上最大的平面镜,由于其复杂的功能,又被称作大型科学可控反射镜(Giant Steering Science Mirror,GSSM)。为了更好地分析与抑制GSSM在实现光线中继功能时的抖动,需要对抖动有精确的测量。由于GSSM抖动的要求特殊且严格,在测量之前,需要对抖动测量的误差进行仔细地分析与理解,才可以更好地完成检测任务。首先,文中针对使用编码器进行抖动测量的情况,在不同的测量方案以及相对距离下,通过蒙特卡洛方法可以得到由激光跟踪仪进行标定的误差:俯仰轴线的定位误差,在轴上测量的期望为1μm,小于轴外测量的3μm;方位轴线的定位误差在激光跟踪仪偏离两米的情况下为4.6μm。之后对加速度计测量抖动的误差进行了考虑,首先推导了使用功率谱方法的完备性条件;之后使用累积功率谱对于333B32的标定结果进行处理,得到当采样频率为2 048 Hz,0.05 Hz以外的频段,其精度为0.6μm。抖动的测量以及误差分析,不仅是GSSM建设过程中十分重要的环节,同时,它可以为大口径望远镜建设提供宝贵的统计学先验知识,并对于系统工程的发展是一种很好的推动。
The 30 m telescope Three mirrors, the largest planar mirror in the world, are also known as the Giant Steering Science Mirror (GSSM) because of their complex function. In order to better analyze and suppress the jitter of the GSSM when implementing the function of light relay, accurate measurement of jitter is required. Due to the special and rigorous requirements of GSSM jitter, it is necessary to carefully analyze and understand the jitter measurement error before measurement, so that the detection task can be completed better. First of all, in this paper, we use the Monte Carlo method to get the error of calibration by the laser tracker in the case of jitter measurement using encoder. The errors of the positioning of the pitch axis, The expectation is 1 μm, which is less than 3 μm measured off-axis; the positioning error of the azimuth axis is 4.6 μm with the laser tracker deviating two meters. After that, the jitter error of the accelerometer was considered. At first, the completeness condition of power spectrum method was deduced. Then the cumulative power spectrum was used to process the calibration results of 333B32. When the sampling frequency was 2 048 Hz, Band, the accuracy of 0.6μm. Jitter measurement and error analysis are not only a very important step in the construction of GSSM, but also provide valuable statistical prior knowledge for the construction of large-aperture telescopes and are a good impetus for the development of system engineering.