Fig. 1. Laser focusing system model

Fig. 2. Laser beam distribution

Fig. 3. Temperature distribution on lens surface

Fig. 4. Stress and deformation of lens

Fig. 5. Deposition power. (a) Deposition power of the lens; (b) deposition power on target surface

Fig. 6. Refractive index change of focusing lens

Fig. 7. Relationship between RMS of point size and position of focal plane. (a) Overall change curves; (b) enlargement in Fig. 7(a)

Fig. 8. Spot diagram of beam on the best focal plane

Fig. 9. Experimental device. (a) Ultraviolet laser processing equipment; (b) ultraviolet laser instrument; (c) processing platform

Fig. 10. Change of focusing spot. (a) Light spot at initial position; (b) stabilized light spot

Fig. 11. Morphologies of cutting areas. (a) Initial cutting area; (b) transition area; (c) initial stable area; (d) ending stable area

Fig. 12. Measurement results of step profiler. (a) Measuring position of step profiler; (b) step morphology

Fig. 13. Morphologies of transition area. (a) 2D morphology; (b) 3D morphology

Fig. 14. Processing depth (ten times). (a) Initial cutting area; (b) stable area