Fig. 1. Pulse function of period diagram

Fig. 2. Mesh generation

Fig. 3. Heat distribution of optical lens under continuous laser action. (a) 1000 W; (b) 3000 W; (c) 5000 W

Fig. 4. Changes in refractive index of optical lens. (a) 1000 W; (b) 3000 W; (c) 5000 W

Fig. 5. Deformation of optical lens when heated for 5 s. (a) 1000 W; (b) 3000 W; (c) 5000 W

Fig. 6. Focus of optical system after beam is heated

Fig. 7. Relationship between continuous laser power and axial focus displacement

Fig. 8. Relationship between quasi-continuous laser power and axial focus displacement

Fig. 9. Relationship between pulse width and axial focus displacement

Fig. 10. Relationship between repetition frequency and axial focus displacement

Fig. 11. Relationship between convection coefficient and axial focus displacement