Mechano-responsive colour change of laser-induced periodic surface structures

Gräf, Stephan; Undisz, Andreas; Wonneberger, Robert; Rettenmayr, Markus; Müller, Frank A.

doi:10.1016/j.apsusc.2018.12.051

Cited by 39 publications

(28 citation statements)

References 31 publications

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“…In addition, the possibility to control the LIPSS distribution within the focal spot by choosing a certain beam profile leads to an extension of the current state-of-the-art and, thus, to a higher flexibility of the direct-writing structuring method. The fluence values calculated above for the top-hat profile are comparable with the fluence required for ablation-based LIPSS formation on stainless-steel at comparable irradiation parameters [30,31].…”

Section: Single-spot Experimentssupporting

confidence: 58%

“…In this context, the specific optical properties make stainless-steel a well-suited candidate for the production of highly regular LIPSS [ 31 ]. This concerns in particular the exact alignment and a small dispersion of the spatial frequencies of the LIPSS, which are coherently linked to each other despite the unidirectional scanning procedure [ 30 , 31 ].…”

Section: Resultsmentioning

confidence: 99%

“…(1) As already demonstrated in [30,31], highly regular LIPSS can also be generated with conventional Gaussian beam profiles. However, the radial intensity dependence and the circular spot area require a larger overlap of the laser pulses in both x-and ydirections to realize an almost homogeneous energy deposition.…”

Section: Laser Surface Structuring On the Nanoscalementioning

confidence: 97%

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Squared Focal Intensity Distributions for Applications in Laser Material Processing

Wilms¹,

Fuchs²,

Müller

et al. 2021

Materials

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Tailored intensity profiles within the focal spot of the laser beam offer great potential for a well-defined control of the interaction process between laser radiation and material, and thus for improving the processing results. The present paper discusses a novel refractive beam-shaping element that provides different squared intensity distributions converted from the Gaussian output beam of the utilized femtosecond (fs) laser. Using the examples of surface structuring of stainless-steel on the micro- and nano-scale, the suitability of the beam-shaping element for fs-laser material processing with a conventional f-Theta lens is demonstrated. In this context, it was shown that the experimental structuring results are in good agreement with beam profile measurements and numerical simulations of the beam-shaping unit. In addition, the experimental results reveal the improvement of laser processing in terms of a significantly reduced processing time during surface nano-structuring and the possibility to control the ablation geometry during the fabrication of micro-channels.

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Section: Single-spot Experimentssupporting

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Section: Laser Surface Structuring On the Nanoscalementioning

confidence: 97%

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Squared Focal Intensity Distributions for Applications in Laser Material Processing

Wilms¹,

Fuchs²,

Müller

et al. 2021

Materials

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“…Macroscopic elastic deformations affect the microscale by slightly changing the periodicity of the gratings responsible for the holographic colors. This has been systematically reported in the recent work of Gräf, where the effects of the work piece's deformation have been correlated with the microscopic deformation of the gratings, thus changing the colors they diffract. For the approaches presented in this work, the surface is patterned with different microgratings, and consequently any macroscopic deformation would modify the periodicity of the microgratings in the same relative amount.…”

Section: Resultsmentioning

confidence: 71%

How to Tailor Structural Colors for Extended Visibility and White Light Generation Employing Direct Laser Interference Patterning

Storm

Alamri

Soldera

et al. 2019

Macro Chemistry & Physics

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The appearance of a surface can be controlled by creating periodic microstructures designed to diffract light and produce structural colors. Nevertheless, since structural coloration is based on diffraction, the produced colors have a strong dependence on the viewing angle and absence of coloration takes place while tilting the samples. In this work direct laser interference patterning is used to firstly provide transparent polymer sheets a structural coloration with a high‐range observation angle, and secondly to demonstrate the combination of structural colors, producing a white coloring effect. The employed approaches are based on the fabrication of micro‐gratings with multiple periods in the same structured area and on the engineering of the diffraction orders of the diffraction spectrum. The patterned surfaces are characterized by confocal microscopy and angular spectrometry in reflection mode. The morphological characterization shows homogeneous surface patterns, while the spectral results demonstrate that combining four spatial periods on a single patterned surface, a white appearance is obtained over an angular observation range higher than 30°. The experimental results are supported by theoretical predictions by means of generalized formulas based on the diffraction of light.

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“…LIPSS [65,66,67,68], a universal phenomenon that occurs after laser irradiation on a wide number of different materials [69,70,71], have been found to exhibit different characteristic shapes, including ripples (lines), rods, cones, grooves, etc. The generation of LIPSS takes place commonly only in a fluence range close to the material damage threshold and even just below the ablation threshold [72].…”

Section: Resultsmentioning

confidence: 99%

Picosecond Laser Interference Patterning of Periodical Micro-Architectures on Metallic Molds for Hot Embossing

Soldera

Wang

et al. 2019

Materials

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In this work, it is demonstrated that direct laser interference patterning (DLIP) is a method capable of producing microtextured metallic molds for hot embossing processes. Three different metals (Cr, Ni, and Cu), relevant for the mold production used in nanoimprinting systems, are patterned by DLIP using a picosecond laser source emitting at a 532 nm wavelength. The results show that the quality and surface topography of the produced hole-like micropatterns are determined by the laser processing parameters, such as irradiated energy density and the number of pulses. Laser-induced periodic surface structures (LIPSS) are also observed on the treated surfaces, whose shapes, periodicities, and orientations are strongly dependent on the accumulated fluence. Finally, the three structured metals are used as embossing molds to imprint microlenses on polymethyl methacrylate (PMMA) foils using an electrohydraulic press. Topographical profiles demonstrate that the obtained structures are comparable to the masters showing a satisfactory reproduction of the texture. The polymeric microlens arrays that showed the best surface homogeneity and overall quality were those embossed with the Cr molds.

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Mechano-responsive colour change of laser-induced periodic surface structures

Cited by 39 publications

References 31 publications

Squared Focal Intensity Distributions for Applications in Laser Material Processing

Squared Focal Intensity Distributions for Applications in Laser Material Processing

How to Tailor Structural Colors for Extended Visibility and White Light Generation Employing Direct Laser Interference Patterning

Picosecond Laser Interference Patterning of Periodical Micro-Architectures on Metallic Molds for Hot Embossing

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