Fig. 1. Ultra-precision laser direct writing system

Fig. 2. Platform error when scanning velocity is 40 mm/s. (a) Error in X direction; (b) deflection error of platform; (c) corresponding scanning velocity of platform

Fig. 3. Schematics of step-scanning exposure. (a) Front view; (b) top view

Fig. 4. Schematic of grating period error in stitching exposure

Fig. 5. Effect of grating period error on stitching exposure contrast when fabricating gratings with grid line density of 1200 line/mm

Fig. 6. Phase error distribution of exposed grating

Fig. 7. Measurement result of corner

Fig. 8. Schematic of measurement for image grating period

Fig. 9. Grating period measurement data

Fig. 10. Schematic of 2D grating mask fabrication

Fig. 11. AFM of 2D grating mask. (a) 3D profile; (b) cross section

Fig. 12. Scanning electron microscopes of grating mask

Fig. 13. 2D grating mask (1200 line/mm)