Fig. 1. Schematic diagram of composite polishing. (a) Femtosecond laser combined with variable angle machining; (b) nanosecond laser processing; (c) ion-beam polishing

Fig. 2. SEM morphologies of diamond surface processed by femtosecond laser under different powers and exposure time

Fig. 3. Variation trend of surface roughness of femtosecond laser processed diamond under different powers and exposure time. (a) Variation of surface roughness with exposure time; (b) variation of surface roughness with power

Fig. 4. Variation trend of roughness under different machining methods. (a) Variation of roughness with incident angle of femtosecond laser; (b) variation of roughness with nanosecond laser power; (c) roughness before and after ion-beam polishing; (d) variation of roughness with ion-beam polishing time; (e) roughness of different processed surfaces

Fig. 5. Scanning electron microscopy and three-dimensional depth-of-field morphologies of diamond surface under different processing methods. (a)(e) Original diamond surface; (b)(f) femtosecond laser processed surface; (c)(g) femtosecond+nanosecond laser processed surface; (d)(h) femtosecond+nanosecond+ion-beam polished surface

Fig. 6. Raman spectra of different processed surfaces