Fig. 1. Structural diagram of surface measurement system

Fig. 2. Diagram of simplified system

Fig. 3. Geometric model

Fig. 4. Enlarged figure of geometrical principle of surface shape measurement

Fig. 5. Optical lattice images acquired by CCD. (a) Flat surface; (b) slope surface

Fig. 6. Flow chart of image processing

Fig. 7. Centroid marking after eliminating incomplete edge cells

Fig. 8. Distribution of centroid position

Fig. 9. Changes of centroid position. (a) x direction; (b) y direction

Fig. 10. Results of surface measurement. (a) Measured by Zygo interferometer; (b) measured by optical lattice deformation method; (c) difference between two methods