基于入瞳中心标定的位相测量偏折术光学元件曲率半径测量

Radius of Curvature Measurement of Optical Element in Phase Measureing Deflectometry Based on Entrance Pupil Center Calibration

对于传统的相位测量偏折术,基于反射定理的测量原理导致其难以完成具有大陡度的大曲率元件曲率半径全口径测量。因此,传统单目偏折术与平面反射镜相结合的测量方法被提出。然而,现有的测量方法中需将安装于显示器上的平面反射镜严格处于45°倾斜状态,并在水平方向与相机光轴的夹角为45°,这无疑使实验装置的调整难度大大增加。提出了一种基于成像透镜入瞳中心标定的测量方法,该方法只需要利用显示器的平移来获得成像相机的入瞳中心即相机的投影中心,而无需精确调整相机和平面反射镜的姿态,操作简单,易于实现。实验中测量了曲率半径均值为8.262 mm的凸球面光学元件,测量得到其每点的平均曲率半径均值为8.321 mm,PV为0.212 mm,相对误差约为0.71%。相比于现有的正入射光路,所提方法不仅实验装置调整难度低,而且还能保证较高的实验测量精度,验证了该方法的可行性。

For conventional phase measuring deflectometry,the measurement principle based on the law of reflection makes it difficult to perform full-aperture measurements of the radius of curvature(ROC)of large dynamic curvature value.Therefore,the traditional monoscopic deflectometry combined with a planar mirror measurement method is proposed.However,the measurement method of the existing method requires the plane mirror mounted on the monitor to be strictly tilted at 45°and the angle of 45°with the camera optical axis in the horizontal direction,which undoubtedly makes the experimental setup more difficult to align.Therefore,the calibration of entrance pupil center of the imaging lens method is proposed in this paper.In the experiment,only the translation of the display is needed to obtain the position of entrance pupil center of the imaging camera lens,without the need to accurately align the posture of the camera and the plane mirror.Finally,a convex spherical optical element with a mean ROC of 8.262 mm is measured in the experiment,and the mean ROC at each point is measured to be 8.321 mm with a PV of 0.212 mm,with a relative error of 0.71%about.Compared with existing normal incident optical paths,the adjustment process is less difficult,but the measurement accuracy of components is still high,which verifies the feasibility of the method.