Fig. 1. Schematic diagram of DOE

Fig. 2. Schematic diagram of manufacturing error of DOE

Fig. 3. Light scattering caused by surface roughness

Fig. 4. Shadow area caused by half-round tool

Fig. 5. Schematic diagram of residual tool mark. (a1)(a2) Original turning model; (b1)(b2) optimized turning model

Fig. 6. Schematic diagram of optimal turning position of half-round tool. (a) Tool tip is lower than workpiece surface; (b) tool tip is higher than workpiece surface

Fig. 7. Relationship between diffraction efficiency and tool radius. (a) Influence of scattering effect on diffraction efficiency; (b) influence of shadow effect on diffraction efficiency; (c) comprehensive influence of manufacturing errors on diffraction efficiency

Fig. 8. Relationship between diffraction efficiency and tool radius under different central wavelengths. (a) λ₀=2 μm; (b) λ₀=3 μm; (c) λ₀=4 μm

Fig. 9. Relationship between optimal tool radius and feed rate under different center wavelengths(point is experimental data, and dotted line is fitted curve)

Fig. 10. Experimental equipments. (a) Turning lathe; (b) half-round tool

Fig. 11. Experimental results. (a) Physical drawing of CaF₂ DOE ; (b) test result of surface profile error; (c) test result of surface roughness error