Alamri Sabri, El-Khoury Mikhael, Aguilar-Morales Alfredo I, Storm Sebastian, Kunze Tim, Lasagni Andrés F
Fraunhofer-Institut für Werkstoff- und Strahltechnik IWS, Dresden, 01277, Germany.
Technische Universität Dresden, Institut für Fertigungstechnik, Dresden, 01062, Germany.
Sci Rep. 2019 Apr 1;9(1):5455. doi: 10.1038/s41598-019-41902-x.
The direct fabrication of microstructures, having a non-symmetrical morphology with controllable inclination, presents nowadays a challenging task. Natural examples of surfaces with inclined topographies have shown to provide anisotropic functionalities, which have attracted the interest of several researchers in the last years. This work presents a microfabrication technique for producing microstructures with a determined and controllable inclination angle using two-beam Direct Laser Interference Patterning. Polyimide foils are irradiated with a 4 ns UV (266 nm) laser source producing line-like structures with a period varying from 4.6 µm to 16.5 µm. The inclinations, retrieved by tilting the sample with respect to the optical axis of the setup, are changed from 0° to 75°, introducing a well controllable and defined inclination of the structure walls. The structuring parameters (laser fluence, number of laser pulses and interference period) as well as the inclination of the microstructures are correlated with the global tilting of the sample. As a result, a determined laser fluence and number of pulses are necessary to observe a remarkable non-symmetrical morphology of the structures. In addition, the presence of structural undercuts is reported, which opens the possibility for developing new direction-dependent properties on polymeric materials. As an example, preliminary results on light diffraction are presented, showing a similar behavior as blazed diffraction gratings.
直接制造具有可控倾斜度的非对称形态微结构，如今是一项具有挑战性的任务。具有倾斜形貌的表面的自然实例已表明能提供各向异性功能，在过去几年中吸引了众多研究人员的关注。这项工作提出了一种微制造技术，利用双光束直接激光干涉图案化来生产具有确定且可控倾斜角度的微结构。用4纳秒紫外（266纳米）激光源照射聚酰亚胺箔，产生周期从4.6微米到16.5微米的线状结构。通过相对于装置光轴倾斜样品来获取倾斜度，倾斜度从0°变化到75°，从而引入结构壁可控且明确的倾斜度。结构参数（激光能量密度、激光脉冲数和干涉周期）以及微结构的倾斜度与样品的整体倾斜相关。结果，需要确定的激光能量密度和脉冲数才能观察到结构显著的非对称形态。此外，报告了结构底切的存在，这为在聚合物材料上开发新的方向依赖性特性开辟了可能性。例如，给出了光衍射的初步结果，显示出与闪耀衍射光栅类似的行为。
