基于多次反射偏振相位法的高分辨率和高精度滚转角测量技术研究

The project is proposed based on multiple reflections and orthogonal polarization phase method, aiming at the problem in the high-resolution and high-precision measurement of roll angle for CNC machine tools. The basic principle is combining the orthogonal polarization phase method and multiple reflection method. Though the phase method, in theory, can achieve a high measurement resolution by setting a smaller ellipsometric parameter, the signal to noise ratio of measurement signal decreases, thus resulting in the lower accuracy and reliability. The multiple reflections method doubles the phase by the polarized light round trip through the phase-sensitive component several times, which achieves high measurement resolution and also ensures the signal to noise ratio and measurement accuracy by setting a larger ellipsometric parameter. So combination of those methods and corresponding optimization can achieve a higher resolution and accuracy simultaneously. Based on this principle, this project will focus on researches of the measurement principle and corresponding technical solutions, system modeling, optimization design, system calibration technology and its on-site quick implementation, major factors and compensation methods of measurement errors and accurate extraction of phase at the high frequency. Finally, the hardware and software of roll angle measurement system will be designed and developed, and they will be integrated into the existing geometric error measurement system of CNC machine. Through this research, a new solution and idea will be provided for high-resolution and high-precision measurement of the roll angle. Thus, it will promote the research and development of high-precision CNC machine tools.

针对数控机床滚转角难以高分辨率和高精度测量的问题，本项目提出了一种基于多次反射的正交偏振相位法以解决该问题。其基本原理是将正交偏振相位法与多次反射法相结合。相位法在理论上可通过选择较小椭偏参数获得较高的测量分辨率，但测量信号信噪比低，造成测量精度和可靠性降低；多次反射法通过使偏振光多次透过相位敏感元件达到相位倍增的目的，实现高的测量分辨率，同时选择较大的椭偏参数，可保证测量信号的信噪比和测量精度；将二者结合并优化，便可同时获得高的测量分辨率和精度。基于该原理，本项目主要研究测量原理与技术方案、系统建模与最优化设计；系统标定技术与现场快捷实现方法；测量误差的主要因素和补偿方法；高频下相位的精确提取。最终，设计、开发测量系统的软硬件，并将该技术与现有数控机床几何误差测量技术相集成。通过本项目的研究，可为滚转角高分辨率和高精度的测量提供了新的解决方案和思路，进而，促进高精度数控机床的研究发展。

数控机床的几何精度测量是其精度评价、等级分类、新产品验收以及误差溯源和补偿的关键。然而，在数控机床的几何误差检测中，滚转角误差的测量非常困难，目前仍缺乏一种行之有效的手段。.本项目提出了一种基于多次反射的偏振相位的激光外差干涉技术的高分辨率的滚转角测量方法，通过琼斯矩阵建立了测量系统的数学模型，对测量系统中1/4波片偏转角θ和光束往返通过1/2波片的次数进行了影响规律的分析，根据分析结果，选择了偏转角θ为2°，通过次数为2次，得到系统理论分辨率为0.031"。接下来，对系统器件的制造及安装误差对测量结果的影响进行了定量分析，结果表明：1/2波片的制造误差对系统放大倍率的影响较为明显，系统的放大倍率随高反镜入射角的变化而变化，并且据此提出了一种采用倾斜高反镜的方法来提高增大测量灵敏度。进而，针对测量系统标定难以现场实现的问题，提出了一种基于激光外差干涉测量技术的集成化、现场标定方法。此外，针对实验中的相位周期性波动问题，建立相应的数学分析模型，揭示了相位波动的原因；进而，提出了解决相位波动的方案；据此介绍了一种基于声光调制器的优化滚转角测量方案，详细分析了各系统参数对测量放大率和测量精度的影响，并计算了测量不确定度。.构建了相应的实验平台，实验验证了倾斜高反镜方案使系统达到了237倍的放大倍率；所提集成化的现场标定方案也与Renishaw XL80激光干涉仪进行了比较，二者的差异小于0.0043°，表明该标定装置具有良好的稳定性和精度；进而，通过选择不同类型探测器和不同频差激光光源，验证了相位波动分析模型及降低相位波动的两种方案；最后，通过构建AOM实验平台验证了基于AOM滚转角测量优化方案的可行性，并达到了0.016"的分辨率，优于原有测量系统性能。.本项目研究的基于多次反射的偏振相位的激光外差干涉测量技术具有结构简单、抗干扰性强等特点，可以被广泛应用于精密检测中，基于该技术进一步探索提高分辨及精度的方法，对解决滚转角精密测量难题具有理论意义和实用价值。