Fig. 1. Schematic of parallel differential confocal axial measurement method

Fig. 2. Confocal axial light intensity differential response curves

Fig. 3. Schematic of calibration method of axial measurement curve

Fig. 4. Experimental platform for parallel differential confocal axial measurement

Fig. 5. Measured axial measurement curve

Fig. 6. Coin sample. (a) Actual picture and partially enlarged picture of coin sample; (b) confocal picture of coin sample in upper defocusing plane; (c) confocal picture of coin sample in lower defocusing plane

Fig. 7. Topography of coin stripes before correction. (a) Three-dimensional view; (b) top view

Fig. 8. Light intensity differential response simulation curve and axial measurement simulation curve with different peak values

Fig. 9. Light spot array images. (a) Light spot array image in focal plane; (b) enlarged view of solid line frame; (c) enlarged view of dotted line frame

Fig. 10. Axial light intensity response curves of each point in one-dimensional line

Fig. 11. Distribution diagram of light intensity peak value in global field of view

Fig. 12. Light intensity differential response curves of each point in one-dimensional line

Fig. 13. Topography of coin stripes after correction. (a) Three-dimensional view; (b) top view

Fig. 14. Three-dimensional topography of coin stripes measured using commercial microscope. (a) Three-dimensional topography of coin stripes; (b) sectional height profile curve of coin stripes

Fig. 15. Three-dimensional image inpainting figure of coin stripes. (a) Before correction; (b) after correction

Fig. 16. Sectional height profile curves of coin stripes before and after correction

Fig. 17. Step standard sample and enlarged picture of measurement position

Fig. 18. Sectional height profile curves of step standard sample before and after correction