PZT移相和CCD非线性对高精度球面面形检测的影响

Effect of PZT phase-shifting and CCD nonlinear on high-precision testing of spherical surfaces

为了提高球面面形的检测精度,对移相菲索干涉仪的球面测量方法中影响高精度球面面形检测的压电陶瓷晶体(PZT)移相误差和电荷耦合探测器(CCD)非线性误差进行探讨.通过理论分析和数值模拟的方法分别对PZT移相误差、CCD非线性误差进行具体分析,着重研究PZT移相误差和CCD非线性误差的综合影响.由五步移相算法,推导得出PZT和CCD的综合误差公式,对影响综合误差大小的主要因素如CCD二次非线性系数、条纹对比度和被检面曲率半径与口径的比值等进行分析.结果表明,提出的控制PZT和CCD综合误差影响的准则和相应的减小误差影响的方法,可以提高球面面形的检测精度.

To improve the measurement accuracy of spherical surfaces,the phase-shifting error of piezoelectric transducer（PZT） and the nonlinear error of charge coupled device（CCD）,which both are the basic errors in the measuring principle of spherical surface testing based on phase-shifting Fizeau interferometer,impacting on high precision testing of spherical surfaces are discussed here.Then PZT phase-shifting error and CCD nonlinear error were analyzed,especially the combined effects of PZT phase-shifting error and CCD nonlinear error were emphatically studied through detailed analysis and simulation.The formula of combined error caused by PZT and CCD was given by the phase-shifting five-Bucket algorithm according to the major factor analysis such as： second-order nonlinear coefficient of CCD,fringe contrast and the ratio of test surface＇s radius of curvature to its diameter.Experiments show that the proposed criterions to control the error and some methods to minimize the error can improve the measurement accuracy of spherical surfaces.