为了实现二维小角度的测量,采用压电陶瓷(PZT)驱动方式,获取运动的干涉条纹。利用数值积分法推导了理想干涉条纹下,条纹宽度、条纹方向角与光电探测器各象限信号相位的关系,解出了各象限相位等效点,并建立了激光光束夹角与条纹形状之间的模型。应用椭圆最小二乘拟合算法,实现了四象限探测器相位信息的有效提取,达到识别条纹宽度和方向角的目的。二维偏转角的测量实验结果表明,该方法能够满足对工作台角度偏转量等精密测量的要求,即使是在干涉条纹形状不规则、工作台运动频率不严格一致的环境下,对条纹形状的识别精度也很高,重复性好。
For realizing two-dimensional angle measurement, PZT driving method is used to get dynamic interference fringes. According to ideal interference fringes, the relationships of fringe width, orientation angle and each phase of four-quadrant photoelectric detector are deduced with the method of numerical integration, and the approximation points of each quadrant phase are obtained. Moreover, the model between laser beam angle and the fringe shape is established. Ellipse least squares fitting algorithm is used to extract phase information from four quadrants detector. Recognition of width and orientation angle of the fringe is realized. Experimental results of two- dimensional angle measurement indicate that the method meets the requirement of high precision angle measurement. Even with the irregular shape of interference fringes or an inconsistent movement frequency of the worktable, the method can still keep high accuracy and good repeatability.