相位测量偏折术(PMD)是近几年在光学测量领域内普遍使用的一种非接触式的高精度测量方法,该方法需要CCD相机拍摄经被测光学元件反射的在显示屏上显示的条纹图,而CCD自身存在的镜头畸变会对测量精度产生一定的影响。为避免这一影响,提出了在梯形畸变和镜头畸变同时存在的情况下保留梯形形状而只校正镜头畸变的矢量Zernike多项式校正方法。该方法首先利用光轴与被拍摄面的交点及相机和被拍摄面的相对位置来求取与光轴垂直的辅助面上的标准图,然后利用矢量Zernike多项式拟合标准图与畸变图的坐标得到二者的映射关系,接着运用得到的映射关系对畸变图进行校正。实验结果表明:提出的畸变校正方法可以有效地降低测量误差,提高测量精度。

Phase measuring deflectometry (PMD) is a kind of non-contact and accurate measuring method used in the field of optical measurement widely. The method needs CCD to record the fringe pattern displayed on the screen then reflected by mirror. The lens distortion owned by CCD will have certain influence on measurement accuracy. In consideration of the influence, this paper proposes a method to correct the lens distortion using vector Zernike polynomial, when the keystone distortion and lens distortion are both existed and only the keystone distortion needs to be kept. The proposed method, firstly, uses the intersection point of the optical axis with the tested surface, and the relative position of camera and the tested surface to calculate the standard map on the auxiliary plane vertical to the optical axis, then applies Zernike vector polynomial to fit the coordinates between the standard map and distortion map and gets the mapping relation between them, finally, uses the mapping relation to correct the distortion map. The simulation experiment verifies the feasibility of proposed method. When the proposed method is used in PMD experiment, the result shows that the proposed method can reduce the measure error and improve the measurement accuracy effectively.