基于相位法的三维测量系统的相移误差分析

摘要

The precise control of grating phase-stepping is the foundation of measuring instrument based on projected grating phase method. In order to eliminate the phase-stepping error,the hardware system is designed for higher precision movement of step-motor. An improved algorithm is introduced based on the traditional four-step phase extracting algorithm. Using the new system,the minimal segmentation for the step-motor becomes 1/128. The improved algorithm is immune to the phase-stepping error since the stable error becomes the intermediate variable that does not influence the phase results. The experiment indicates:the improved hardware system is easier to operate;the improved algorithm restrains the movement error and then enhances the accuracy,reliability and the system's performance.%采用投影栅相位法进行三维测量时,光栅移动的精密控制是整个测量系统的基础.针对相移误差,对硬件系统进行设计,通过步进电机细分控制实现更小、更平稳的相移误差;并对传统的四步相位提取算法进行优化,在优化算法中,稳定的相移误差项可以作为中间变量,即其大小随机变化不再对相位计算结果产生影响.实验结果表明:设计的硬件系统调试简单,步进电机可以实现最小1/128细分;优化后的算法有效地抑制了相移误差对测量结果的影响,进一步提高了表面微观形貌的测量精度和可靠性;从而使得测量系统的整体性能指标得到提升.