高精度丝径测量中的偏振效应

THE EFFECT OF LIGHT POLARIZATION ON HIGH ACCURACY MEASUREMENTS OF THIN WIRE DIAMETER

本文主要研究光束偏振方向对高精度丝径测量的影响,将给出简要的实验结果:钢丝直径的实测值随光振动方向与细丝轴线的夹角呈正弦变化;振动平行细丝轴线的偏振光的实测值比垂直的小0.36μm;钢质狭缝宽度测量结果则与钢丝情况相反。在此基础上着重对这种影响进行了理论分析。计及细丝表面反射和不同偏振方向光波反射时产生的不同位相变化,细丝的夫琅和费衍射图也发生了微小的改变,致使直径测量值不同。由此对钢丝的分析表明：光振动平行千丝轴时的直径理论值比季直的小 0.33μm，与实验值 0．36μm。相差 0．03μm；光振动平行缝边时的宽匿理论值比垂直的大0．19μm，与其实验值0．21μm相差0，02μm。它们都接近或小于仪器的测量误差0．04μm，理论与实验符合得很好．

The effect of light beam polarization on high accuracy measurements of thin wire diameters has been studied. The experimental results are given below in brief. The experimental magnitudes of steel wire diameters vary sinusoidally with the angle between the direction of light vibration and the wire axis. The experimental value obtained with parallel polarization, (i.e., its vibration being parallel to the wire axis) is 0.36 μm smaller than that of the perpendicular, case. The experimental results of steel slit width are contrary to that of steel wires. Based on the experiment, the theoretical analyses of the polarization effect are carried out. Taken into account the influence of light reflection on the wire surface and different phase changes of different vibration directions produced in the reflection, the Fraunhofer diffraction patterns are slightly changed, therefore making the measured values different. According to this idea, the analysis for steel wire shows: the theoretical value of thin wire diameter for light vibration parallel to the wire axis is 0.33μm smaller than that of perpendicular vibration, different from the experimental value 0.36 μm by 0.03 μm. For steel slit width, the measured value with the light vibrations parallel to slit edges is 0.19 μm larger than that of perpendicular case, different from the experimental value 0.21μm by 0.02μm. These differences between theory and experiment are close to or smaller than the error of the measurement system, 0.04 μm. Good coincidencl is achieved.