Fig. 1. Structure of shield. (a) Top view; (b) right side view

Fig. 2. Structural diagram of honeycomb

Fig. 3. Relative position of shield, fundamental frequency laser and third-harmonic generation laser

Fig. 4. Convergent light source produced by ideal lens group

Fig. 5. Design residual error of ideal lens group

Fig. 6. Diagram of convergent light source

Fig. 7. Diagram of detector

Fig. 8. Optical path of strayed light analysis of shield

Fig. 9. Analysis results of strayed light. (a) Intensity distribution of light in solid angle; (b) illuminance distribution of returned light

Fig. 10. Analysis results of strayed light when D=0.6 mm. (a) Intensity distribution of light in solid angle; (b) illuminance distribution of returned light

Fig. 11. Analysis results of strayed light when D=0.8 mm. (a) Intensity distribution of light in solid angle; (b) illuminance distribution of returned light

Fig. 12. Analysis results of strayed light when D=1.2 mm. (a) Intensity distribution of light in solid angle; (b) illuminance distribution of returned light

Fig. 13. Analysis result of strayed light when D=1.4 mm. (a) Intensity distribution of light in solid angle; (b) illuminance distribution of returned light

Fig. 14. Relationship between results received by detector and diameter of honeycomb

Fig. 15. Relationship between results received by detector and spacing of honeycomb