Laser surface micro-/nano-structuring by a simple transportable micro-sphere lens array

Abstract

International audienceA micro-sphere array optic was employed for laser surface micro-structuring. This array optic consists of a hexagonally close-packed monolayer of silica micro-spheres. It was organized through a self-assembly process and held together on a glass support, without using any adhesives. The array assembly was then reversed, placed in direct contact with the substrate and exposed to 515 nm, 6.7 ps laser pulses. During the exposure, the silica spheres act as micro-lenses, which enhance the near-field light intensity underneath them. As the spheres are confined in the space between the substrate and glass support, they are not ejected during laser machining. Using this type of direct write laser machining, a large number of identical features (nano-holes) can be produced in parallel simultaneously. The holes drilled are a few hundred nanometres in diameter and the depth depends on the number of laser pulses applied. The impact of laser machining on the micro-spheres was also studied. The micro-spheres were contaminated or partially damaged after micro-structuring. Combination of a moderate laser pulse energy and multiple shots was found to ensure a good surface structuring quality and minimum damage to the spherical particles. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4767471

Subwavelength Direct Laser Nanopatterning Via Microparticle Arrays for Functionalizing Metallic Surfaces

“…Further irradiation of nanoholes fabricated with single-pulses with fluences in the range from 0.18 to 0.29J/cm 2 , as shown in Figure 2g, did not lead to additional material removal but resulted in some improvements of nanoholes' rims, as already reported [24,54]. The irradiation intensity was sufficient to displace the microspheres from their initial locations and thus to prevent the fabrication of nanoholes with higher aspect ratio unless preventing such displacements [36]. Figures 3h-i), which could be of interest for a single-step LIPSS fabrication.…”

“…Contrary to laser cleaning where the laserinduced marking is an undesirable side-effect, to achieve large-area PN texturing the marking must be maximized while minimizing the microspheres' detachment. Several techniques were proposed to address this issue, usually by preserving CPLA by covering it with a transparent material [33][34][35][36]. Maintaining CPLA in contact with the substrate allowed multi-pulse processing and thus to texture larger areas homogeneously and at the same time to increase the aspect ratio of the resulting nanoholes [36].…”

Nanopatterning with Photonic Nanojets: Review and Perspectives in Biomedical Research

“…Nonetheless, optical absorption in the UV or material heating at longer wavelengths caused by polymeric/adhesive carriers can limit the range of light sources suitable for nanopatterning. Alternatively, the sphere array can be prepared onto a glass substrate that, after being flipped upside down, is placed in direct contact with the substrate [ 87 ]. The resulting transportable array is transparent over a wide spectral range.…”

Mechanical durability of hydrophobic surfaces fabricated by injection moulding of laser-induced textures

“…Finally, micro scale ablation was used to manufacture lotus-inspired morphologies with different aspect ratios and grid structures by varying the spatial distance between intersecting grooves. The process settings used to laser texture eight inserts (detailed in Table 1) were selected based on reported results [7,10,[22][23][24][25] and some preliminary trials. After the laser texturing operation, the inserts were first sonicated in ethanol bath for 15 min and then rinsed with water and air dried.…”