Fig. 1. Geometric structure diagrams of SiC CRL with parabolic cylinder holes. (a) Unit structure diagram of lens with parabolic cylinder holes; (b) schematic of SiC CRL with parabolic cylinder holes composed of N′ units

Fig. 2. Functional optimization of femtosecond laser processing platform. (a) Designed blowing head; morphologies of same CRL unit taken during processing on (b) 20th, (c) 40th, and (d) 60th layers

Fig. 3. Schematics of straight line segment and arc approaching parabolic path. (a) Straight line segment approaching; (b) arc approaching

Fig. 4. Machining strategy based on contour offset.

Fig. 5. Machining strategy based on line scanning.

Fig. 6. Schematics of composite path processing strategy

Fig. 7. Schematics of machining flow of SiC CRL with parabolic cylinder holes. (a) Pre-drilling; (b) front processing of composite path; (c) ultrasonic cleaning; (d) reverse processing of composite path; (e) overall shape cutting; (f) ultrasonic cleaning

Fig. 8. SEM morphologies of SiC CRL with parabolic cylinder holes. (a) Overall morphology; (b) enlarged morphology of front part shown in box; (c) enlarged morphology of reverse part shown in box; (d) side wall morphology taken from direction of arrow

Fig. 9. Morphological data of SiC CRL with parabolic cylinder holes. (a) Contour ; (b) roughness

Fig. 10. Focusing effect and analysis of SiC CRL with parabolic cylinder holes processed by femtosecond laser. (a) Focal spot photo; (b) spot intensity distribution; (c)‒(e) cross-section light intensity distributions; (f) total intensity distribution of spot along Y direction