Fig. 1. Laser processing system (insert: scanning strategy)

Fig. 2. Parallel section morphologies of PBO fiber-reinforced composites processed by UV picosecond laser. (a) Macroscopic section picture; (b) microscopic section picture; (c) SEM picture

Fig. 3. Vertical section morphologies of PBO fiber-reinforced composites processed by UV picosecond laser. (a) Macroscopic section picture; (b) microscope section picture; (c) SEM picture of upper section; (d) SEM picture of bottom section

Fig. 4. Section pictures of PBO fiber-reinforced composites processed by IR picosecond laser. (a) Upper part of vertical section; (b) middle part of vertical section; (c) bottom part of vertical section; (d) parallel section

Fig. 5. Molecular structure of PBO fiber and epoxy resin. (a) PBO fiber; (b) epoxy resin

Fig. 6. SEM pictures of cutting section after adjusting parameters. (a) Upper part of section; (b) middle part of section; (c) bottom part of section

Fig. 7. Influence of laser power on kerf depth under different conditions. (a) The laser scanning direction is parallel and perpendicular to the fiber axial direction; (b) with and without compressed air

Fig. 8. Circular cutting of PBO fiber-reinforced composite. (a) The upper surface parallel to the axial direction of fiber; (b) parallel section photo; (c) the upper surface perpendicular to the axial direction of fiber; (d) vertical section photo

Fig. 9. Variation of kerf depth with scanning speed and the comparison of laser processing efficiency at different scanning speeds. (a) Variation of kerf depth with scanning speed; (b) kerf depth at different scanning speeds

Fig. 10. Illustration of spot overlapping

Fig. 11. Variation of kerf depth with pulse repetition rate