基于体式显微镜和数字图像相关法，提出并实现了一种用于对微小尺度材料进行全场三维变形测量的显微数字图像相关系统。针对体式显微镜标定，提出一种高精度的基于B样条曲面重构的成像系统畸变模型，该模型通过采集自主设计的高精度平面标定板图像，来构建无畸变图像平面和标定板平面之间关系，并以此确定空间B样条曲面形式。利用一种高效的对称亚像素细分法来实现数字图像的高精度匹配，并介绍了所提系统进行三维测量和分析的过程。实验结果表明，标定结果的平均重投影误差为0.03 pixel，位移测量精度优于0.2 μm，应变测量误差的标准差不超过100 με。同时，实验结果也证实了该系统可以准确、全面地实现对微小尺寸材料表面的全场三维变形测量。

A novel microscopic full field three-dimensional deformation measurement system is proposed and implemented, which is based on stereo microscope and digital image correlation method. In order to realize the calibration of stereo microscope, a new high precision distortion model is offered by reconstructing a B-spline surface. By acquiring images of the high precision planar calibration target designed independently and constructing the relationship between the target plane and the free distortion image planes, a form of space B-spline surface is established. Then, a high-efficiency image correlation method is realized by using a symmetric sub-pixel refinement strategy. The process for three-dimensional measurements using the proposed system is presented. Experimental results show that, the root-mean-sqsuare (RMS) error of the calibration results for stereo microscope system is 0.03 pixel, the displacement measurement accuracy is better than 0.2 μm, and the standard deviation of strain measurement error is no more than 100 με. At the same time, the experimental results indicate that the proposed system is accurately and can solve the problem of microscopic full field three-dimensional deformation measurement comprehensively.