LIPSS-based functional surfaces produced by multi-beam nanostructuring with 2601 beams and real-time thermal processes measurement

Abstract

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.

Formation of picosecond laser-induced periodic surface structures on steel for knee arthroplasty prosthetics

“…The surface functionalization that can be achieved in a singlestep process when creating LIPSS can change optical, mechanical, or chemical surface properties (Hauschwitz et al, 2021). For instance, control of the wetting properties of stainless steel was achieved using LIPSS created at different laser fluences (Indrišiūnas et al, 2022).…”

Towards mass production of functionalized plastic components via multi-beam nanostructuring of moulds

“…Despite this progress, the capacity to produce micro and nanoscale surface features over large areas represents a significant challenge in terms of production technology, throughput and cost. In the last years, multi-beam technology was proven to significantly improve productivity by parallelization into more than 1000 simultaneously structuring laser beams [10][11][12][13][14]. However, for components with a complex 3D geometry lower number of beams or complex strategies have to be applied, which decreases the throughput.…”

Influence of Heat Accumulation on Morphology Debris Deposition and Wetting of LIPSS on Steel upon High Repetition Rate Femtosecond Pulses Irradiation

“…For the so called LSFL, this periodic intensity translates into an ablation pattern of parallel structures with spatial dimensions ranging from nanometers up to several microns. Although the process is material-dependent [ 5 ], the study of the main processing parameters that lead to the formation of LIPSS have been identified for various metals, semiconductors and dielectrics [ 1 ], including material properties (optical [ 6 , 7 ], thermal [ 8 ], chemical [ 9 ]), processing conditions (number of effective pulses per spot unit [ 10 , 11 , 12 ], scanning direction vs. polarization [ 13 ], over-scanning [ 14 ], irradiation atmosphere [ 15 ], surface polishing [ 16 ], substrate temperature [ 17 , 18 ], material thickness [ 19 , 20 ]) and laser source parameters (wavelength [ 21 ], pulse duration [ 22 ], beam polarization [ 23 ], angle of incidence [ 24 ], and number of beams [ 25 , 26 ]). Lately, the increasing availability of affordable and stable high-repetition rate femtosecond lasers have been placed under the spotlight, with the laser repetition rate as a key processing parameter to investigate in detail [ 27 , 28 , 29 , 30 , 31 , 32 , 33 ].…”