2ステップアブレーションプロセスの特許出願済も用い、ステンレス鋼表面に周期サイズが均一なナノ格子を形成することができました。その表面色を評価したところ、従来の手法よりもカラーバリエーションが豊富で、かつ明るいことがわかりました。本手法を用いることにより、より発色性の高く、高輝度なレーザーカラーマーキングへの応用が期待されます。
Using the two-step ablation process with femtosecond (fs) laser pulses, a homogeneous nanograting with a uniform period was formed on the stainless steel. The surface color was evaluated with a photograph taken as functions of an incident angle of white light and an observation angle. We have found that the color has more variation and brightness than that of the surface with a non-uniform periodic nanostructure produced with the single-beam fs laser pulses. The results show that the nanograting can spatially disperse well the incident light into individual wavelength owing to the diffraction with high efficiency. Calculation using the grating equation reproduced the characteristic change of the colors observed as functions of these angles.
関連発表：Structural coloration of a stainless steel surface with homogeneous nanograting formed by femtosecond laser ablation (Yoshiki Tamamura & Godai Miyaji) Optical Materials Express (2019)