A unique combination of the ultrashort high-energy pulsed laser system with exceptional beam quality and a novel Diffractive Optical Element (DOE) enables simultaneous production of 2601 spots organized in the square-shaped 1 × 1 mm matrix in less than 0.01 ms. By adjusting the laser and processing parameters each spot can contain Laser Induced Periodic Surface Structures (LIPSS, ripples), including high-spatial frequency LIPSS (HFSL) and low-spatial frequency LIPSS (LSFL). DOE placed before galvanometric scanner allows easy integration and stitching of the pattern over larger areas. In addition, the LIPSS formation was monitored for the first time using fast infrared radiometry for verification of real-time quality control possibilities. During the LIPSS fabrication, solidification plateaus were observed after each laser pulse, which enables process control by monitoring heat accumulation or plateau length using a new signal derivation approach. Analysis of solidification plateaus after each laser pulse enabled dynamic calibration of the measurement. Heat accumulation temperatures from 200 to 1000 °C were observed from measurement and compared to the theoretical model. The temperature measurements revealed interesting changes in the physics of the laser ablation process. Moreover, the highest throughput on the area of 40 × 40 mm reached 1910 cm2/min, which is the highest demonstrated throughput of LIPSS nanostructuring, to the best of our knowledge. Thus, showing great potential for the efficient production of LIPSS-based functional surfaces which can be used to improve surface mechanical, biological or optical properties.
Laser surface texturing is a promising technology for future wide applications of functional surfaces with specific properties like hydrophobic, antibacterial, adhesive, self-cleaning, anticorrosion, light absorbing, low friction, etc. Great advancements have been made in this field in the last few years, but in most cases, it takes from minutes up to 1 h to produce 1 cm2 of a functional surface. Even the availability of high-power ultrashort pulsed lasers in the last few years did not dramatically increase productivity, because there are physical limitations of current processing methods: heat accumulation and oxidation, plasma shielding effect, and precision at high speeds. In order to solve these limitations, there have been developed a new method called a shifted laser surface texturing (sLST) method. The new method has a potential to be at least 100 times more productive with no heat accumulation effect and virtually unlimited number of complex shape objects produced with high precision on the surface. In the present work, the principle and advantages of the method are described. The results of the method are compared with two standard methods (path filling of objects and hatch over all objects). The sLST method is presented in both single pulse and burst variants. Examples of its application on different materials for increased adhesion of surface coatings are shown.
Antireflection microstructured surface were fabricated on ZnSe through a rapid and scalable method which was called femtosecond laser direct writing (FsLDW). With this technology, micrometer level inverted pyramid and cone arrays were fabricated precisely. The measured transmittance were about 11.3% higher compared with the plain ZnSe at 9μm in the ideal situation. These results were in good accord with the simulations which were calculated by geometric and diffractive field tracing techniques.
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