显微三维数字图像相关系统中体视显微镜景深小,光路复杂,宏观标定方法不适用于该系统。针对此问题,提出一种适用于显微立体视觉的定点旋转标定方法。基于体视显微镜放大倍率与景深的关系,建立数学模型,得到标定板与XY平面间的最大夹角,设计定点旋转平台对标定板进行旋转标定,通过系列实验对标定参数进行优化,得出使标定参数整体误差最小的夹角。标定结果表明,主点坐标误差不超过1.8 pixel,Z分量相对平移向量的最大偏差值小于0.15 mm,姿态数为10或10以上时标定结果趋于稳定。借助于精密位移台对标定结果进行了精度验证,结果表明采用所提方法标定后位移测量的平均相对误差为2.2%,平均均方差为0.36 μm。

The macroscopic calibration method cannot be applied in the microscopic three-dimensional digital image correlation system due to the small depth of field and the complex optical paths of a stereo microscope. As for this problem, a fixed-point rotation calibration method is proposed, which is suitable for microscopic stereo vision. The mathematical model is established based on the relationship between magnification and depth of field, and thus the maximum angle between calibration plate and XY plane is obtained. In addition, the fixed-point rotation platform is designed to calibrate the calibration plate. The calibration parameters are optimized by a series of experiments and the inclination angle used for minimizing the overall error of the calibration parameters is obtained. The calibration results show that the main point coordinate error is not larger than 1.8 pixel, the maximum deviation of the relative translation vector of Z component is less than 0.15 mm, and the calibration result tends to be stable when the attitude number is 10 or above. The accuracy of the calibration results is tested by use of a precision displacement platform and the results show that the average relative error of displacement measurement by the proposed method is 2.2% and the mean square error is 0.36 μm.