Fig. 1. Microscopic three-dimensional digital image correlation system

Fig. 2. Chess board calibration plate

Fig. 3. Fixed-point rotation platform. (a) CAD diagram; (b) physical drawing

Fig. 4. Optical path of stereo microscope

Fig. 5. Relationship between inclination angle and depth of field

Fig. 6. Process of image acquisition of calibration plate. (a) Fixed-point rotation of calibration plate; (b) image acquisition of calibration plate (left CCD)

Fig. 7. Schematic of main point calibration. (a) Calibration images under different magnification; (b) fitting of projection point coordinates

Fig. 8. Main point coordinates for 22 times calibration

Fig. 9. Reprojection errors

Fig. 10. Rotation angle of calibration plate around Z axis when intervals of calibration plate rotation around Z axis are 5°, 10° and 15°, respectively. (a) Left sub optical path; (b) right sub optical path

Fig. 11. Relative translation quantities of left and right sub optical paths. (a) Calibration plate rotating around Z-axis with 5°; (b) calibration plate rotating around Z-axis with 10°

Fig. 12. Overall errors of calibration board under different attitudes

Fig. 13. Influence of attitude number of right CCD on stability of calibration results. (a) Focal length versus attitude number; (b) main point coordinate versus attitude number; (c) radial distortion coefficient versus attitude number; (d) relative error versus attitude number

Fig. 14. Three-dimensional average displacement vector

Fig. 15. Picture of coin

Fig. 16. Coin speckle maps from left and right CCDs. (a) Left CCD; (b) right CCD

Fig. 17. Three-dimensional shape measurement chart of coin