Fig. 1. Principle of large-area marking based on filamentation. (a) Photograph of filamentation taken by CCD; (b) schematic of expanding marking range based on laser filamentation

Fig. 2. Schematics of laser marking system. (a) Schematic of femtosecond laser filamentation marking system; (b) schematic of flat-field focusing laser marking system

Fig. 3. Result of marking experiment with resolution plate array. (a) Sample processed by flat-field focusing laser marking system; (b) magnification of region boxed in Fig.3(a)

Fig. 4. Widths of the lines marked at different positions in Z direction

Fig. 5. Result of marking experiment with resolution plate array. (a) Sample processed by femtosecond laser filamentation marking system; (b) magnification of region boxed in Fig.5(a)

Fig. 6. Marking resolution. (a) Marking resolution of flat field focusing laser marking system; (b) marking resolution of femtosecond laser filamentation marking system

Fig. 7. Laser making on sphere. (a) Schematic of maximum range for marking on sphere; (b) marking image on surface of stainless steel ball

Fig. 8. Correction of marking distortion on sphere and marking resolution on sphere. (a) Pre-marked resolution plate array; (b) resolution plate array obtained by projection calculation; (c) sample marked by projected image; (d) magnification of region boxed in Fig.8(c); (e) marking resolution on sphere