介绍了一种测量导轨直线度误差的新方法, 利用偏振干涉原理调制出一束偏振角随光束横向坐标线性变化的特殊线偏振光光束, 通过一个随直线度误差移动的光缝测量出光束中不同位置的偏振角, 根据直线度误差与偏振角之间的线性关系, 实现对直线度误差的测量。从理论上对该方法进行了论证分析, 进而详细介绍了光学调制器的组成, 设计了偏振角测量的光电组件, 并进行了相应的实验。实验结果分析表明, 该实验装置的直线度误差与偏振角之间的直线拟合相关指数R2优于0.9995, 且测量直线度误差范围不低于0.5 mm,构建的测量系统经标定后测量分辨力可以达到亚微米级, 测量不确定度达到1 μm。该方法不仅实现方便、可靠性较高, 而且可以克服测量时由于光强变化、导轨形面误差对测量结果的影响, 稍加改进即可实现二维直线度误差测量, 测量精度与自准直仪相当, 具有一定的理论研究意义和较强的实际应用前景。

A new method of measuring guide straightness error is proposed. Based on a linear relationship between polarizing angle and lateral offset position displacement. A peculiar polarized beam, whose polarization angles are distributed linearly as lateral direction coordinates, is modulated by a designed active optical modulator based on polarization interference principle. The polarizing angles of the beam are detected by an optical detecting component and an optical slit, which move correspondingly with the existed guide straightness error. Laboratory experiments are conducted to validate the method and the results show that the correlation coefficients of the linear fitting curves between the polarizing angle and offset displacement is above 0.9995, with the standard deviation of the repeatability test within 1 μm. The range of straightness error measurement is above 0.5 mm with the resolution level at submicron grade. This method minimizes the effects caused by the variation of light intensity and guide surface error and possesses the advantages of convenience, high reliability and accuracy. After modification, it can measure two-dimensional straightuess error with the same precision as the autocollimator. It can be applied to actual industrial applications.