Fig. 1. Deterministic tool path. (a) Grating tool path; (b) Helix tool path

Fig. 2. Diagram of a pseudo-random tool path

Fig. 3. Roughness test by Zygo newview 9000 white-light interferometry

Fig. 4. Measurement results of white-light interferometry before machining

Fig. 5. Measurement result of white-light interferometry after grating trajectory processing

Fig. 6. PSD curve calculated by data of grating trajectory

Fig. 7. Roughness result after processing with pseudo-random trajectory

Fig. 8. PSD curve calculated by data of pseudo-random trajectory