五角棱镜角度误差对建立大尺寸平面基准的影响

用一准直光束作为基线，通过９０°折转的五角棱镜扫描，建立一个参考基准面在大尺寸测量中是一种行之有效的方法。在理想条件下，五角棱镜的折转角不受入射角的影响。由于有加工误差，光束的折转角将偏离９０°，且入射光线与扫描轴间的角运动也会影响该偏转角。本文分析了五角棱镜角度误差和扫描精度对光束折转角的影响。结果表明，五角棱镜的制造误差和工作状态将引起测量带误差，该误差是一个固定的系统误差，可以通过预先对所用的五角棱镜进行标定，在数据处理中予以修正。实验结果表明，修正后的结果具有很高的精度

Study on affection of the angle errors of pentagonal prism on establishing datum plane

It is a effective way using an aligned beam as a baseline and scanning a 90° pentagonal prism to establish a datum reference plane in large dimension measurement. Under an ideal condition, the exiting beam from a pentagonal prism is always perpendicular to its incident beam. Indeed, for there are angle making errors in a pentagonal prism, the bending angle of it is not a right angle again. The incident angle change will cause the bending angle change. This paper analyzes the affection of the making angle errors of a pentagonal prism on the bending angle. The results show that the angle making errors and the working state of a pentagonal prism will cause error in measurement and this error is a fixed system one which can be compensated by calibrating it in advance and data processing method. The experiment result shows that a high measuring accuracy is achieved.