We present a novel method to accurately measure the flatness of a large flat. The method can be seen as a task-specific error correction of the laser tracker. Laser trackers are positioned at two specific measuring stations and measure the coordinates of the same sample points. The angular errors of the primary laser tracker are compensated with constraint information provided by an additional laser tracker. Using this method, we measure the flatness of a 4.5 m flat. The flatness measurement uncertainty is 1.4 µm in rms (root mean square).

中文翻译：

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两站式激光跟踪仪测量大型平板的平面度

我们提出了一种新颖的方法，可以准确地测量大平面的平坦度。该方法可以看作是激光跟踪器的特定于任务的错误校正。激光跟踪仪位于两个特定的测量站，并测量相同采样点的坐标。主激光跟踪器的角度误差通过附加的激光跟踪器提供的约束信息进行补偿。使用这种方法，我们测量了一个4.5 m平面的平面度。平坦度测量不确定度为1.4 µm（均方根）（均方根）。