AVS 65th International Symposium & Exhibition
    Surface Science Division Tuesday Sessions
       Session SS-TuP

Paper SS-TuP13
Variation of Structure Colors of Copper with LIPSS( Laser-Induced Periodic Surface Structure) by Femtosecond Laser Irradiation

Tuesday, October 23, 2018, 6:30 pm, Room Hall B

Session: Surface Science Division Poster Session
Presenter: TaeHoon Park, Korea Institute of Industrial Technology (KITECH), Republic of Korea
Authors: T.H. Park, Korea Institute of Industrial Technology (KITECH), Republic of Korea
J.H. Kim, Korea Institute of Industrial Technology (KITECH), Republic of Korea
T.Y. Hwang, Korea Institute of Industrial Technology (KITECH), Republic of Korea
J.J. Kang, Korea Institute of Industrial Technology (KITECH), Republic of Korea
K.B. Kim, Sejong University, Republic of Korea
H.S. Lee, Korea Institute of Industrial Technology (KITECH), Republic of Korea
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The Laser-Induced Periodic Surface Structure (LIPSS) formed under femtosecond laser irradiation has been a way to change optical, tactile, hydrophobic properties, etc. without chemical reaction. Specially, the LIPSS can be applied to enhance the visual perception of skin materials in order to meet the user’s aesthetic choice of mobiles, auto vehicles, electronics, etc. It has been reported through many studies that the structure color by LIPPS is due to the refraction of the light by periodically nano-scaled structure, however, its variation of structure colors has not been studied generally on the microstructures such as pitch and depth of nano-scaled microstructure. In this study, the metal substrates consisting of pure copper were processed with the condition of femtosecond laser irradiation with the scan rate from 4 mm/s to 20 mm/s and the scan space of 40 µm. The color difference (ΔE) of periodically nano-scaled structure obtained by femtosecond laser irradiation was measured by a multi angle spectrophotometer and quantified by the value of L*a*b* chromaticity diagram. The periodically nano-scaled structures of pure copper showed the roughness (Ra) from 29 nm to 50 nm at the pitch of approximately 280 nm. The brightness was decreased as 15% with an increase of roughness due to a diffused refraction from the surface. The value of L* was ranging from 4 to 81, a* was from 4 to 19 and also b* was from 2 to 24 in the chromaticity diagram of pure copper as detected with tilt angles of 15° to 110°. The calculated ΔE from these results were widely shown from 1.5 to 77, which means that distinctive colors can be realized although the composition of material is not different. It could be expected that the structure color was sufficiently controlled by the periodically nano-scaled structures from femtosecond laser process, and was to be applied at various skin materials.