Fig. 1. Schematic of interference effect for thin film

Fig. 2. CIE Lab color space^[23]

Fig. 3. Laser induced titanium alloy coloring experimental platform

Fig. 4. Effect of speed percent change on formation color stability. (a) Physical map of sample test; (b) image with titanium alloy background removed; (c) graph of ∆Eab* parameter

Fig. 5. Effect of power change by same value on formation color stability. (a) Physical map of sample test; (b) image with titanium alloy background removed; (c) graph of ∆Eab* parameter

Fig. 6. Effect of hatching distance change by same value on formation color stability. (a) Physical map of sample test; (b) image with titanium alloy background removed; (c) graph of ∆Eab* parameter

Fig. 7. Microscopic morphologies of titanium oxide layer under laser confocal microscope. (a) Orange sample; (b) blue sample;

Fig. 8. Microstructures of titanium oxide layer cross-section under scanning electron microscope. (a) Orange sample; (b) blue sample;

Fig. 9. XRD patterns of titanium alloy substrate and titanium oxide layers formed under different laser process parameters

Fig. 10. EDS composition analysis of titanium oxide layer. (a) Orange sample; (b) blue sample; (c) golden sample; (d) purple sample;