在以激光干涉方法进行轴承滚珠面型误差测量时,为避免特制参考标准球面镜自身球度误差对测量结果的影响,提出了一种以平面镜代替球面镜的泰曼-格林轴承滚珠面形误差干涉测量方法,并设计了相应的测量系统。该方法基于相移干涉原理,通过计算机控制压电晶体使参考平面镜获得固定步数的位移,以获得多幅干涉图像,使用电荷耦合图像传感器(CCD)对得到的干涉图像进行采集,系统对获取图像进行相位提取解包裹运算以得到球面的面型误差。对于测量中由轴承滚珠定位精度而引起的离焦、倾焦调整误差,采用泽尼克多项式波面拟合的方法来消除其对测量结果的影响。实验表明,该系统的测量结果与ZYGO干涉仪所得到的结果相比较,峰峰值相差0.001 6λ,均方根误差相差0.004λ,能够有效地对轴承滚珠面型进行检测,且测量结果具有较高的可靠性。此外,该方法还可进一步推广应用于其他需要进行圆球度测量的领域,具有广泛应用前景。
To avoid the influence from sphericity error of spherical mirror on the results in bearing ball measurement with laser interferometry, a Tyman-Green interference method by a plane reference mirror instead of a spherical mirror for the spherical surface error measurement of bearings ball is proposed and a prototype interferometer is developed. Following phase shifting interferometry principle, the interferometer system controls piezoelectric ceramic transducer phase shifter to move the plane reference mirror to obtain more interference images. The images are captured by charge-coupled device camera and then the spherical surface error is evaluated by phase unwrapping. Zernike polynomials fitting is chosen to eliminate the alignment errors from out-off-focus. Experiments verify its effectiveness and robustness, and the root mean square difference of results between surface error measurement system and ZYGO interferometer system is 0. 004λ while the difference of peak-to-peak value is 0. 001 6λ between the two systems. The method can be expected to apply to the other fields of roundness measurement.