| Abstract [eng] |
The potential of glass in high-tech industries such as photonics, microfluidics, and micro-electromechanical systems is significant. Furthermore, the demand for complex-shaped glass elements is constantly increasing. Traditional methods of surface shaping are not meeting modern needs, leading to a rise in laser technology for glass processing. Laser ablation allows precise material processing, improved surface quality, and faster production of glass elements. However, glass is brittle material with good thermal insulation properties. Thus, laser processing has some challenges leading to thermal accumulation and stress formation which can cause glass cracking. Fortunately, the quality of direct ablation depends on the laser pulse duration with femtosecond laser pulses being superior for micro-processing. The resulting microstructures may require further surface smoothing for optical applications which can be achieved through laser polishing. This study aim was to investigate the ablation process of fused silica glass for forming lens arrays using 1030 nm femtosecond and 10,6 μm CO2 laser radiation. Ablation experiments were conducted to create high quality and low roughness surfaces. System parameters were optimized for precise surface shaping. Optimal polishing parameters for lens array polishing were determined using 10,6 μm CO2 laser radiation. Experiments were carried out to optimize parameters such as laser scanning speed, average laser power and defocus distance. After conducing various experiments, it was found that the ablation threshold of fused silica is Fth = 4,28 J/cm2. Single layer glass ablation resulted in the lowest surface roughness of Ra = 87 nm. For this, 209,3 kHz pulse repetition rate, 2000 mm/s scanning speed, 13.3 J/cm2 fluence, and 7,5 μm distance between scanning lines (hatch) were used. Furthermore, laser polishing was optimized too. CO2 laser polishing parameters was found: 60 mm defocusing distance, 10 kHz pulse repetition rate, 7,17 mJ pulse energy, 30 μm hatch, and 300 mm/s scanning speed. Finally, the micro-lens array was formed and polished. Polishing step reduced surface roughness Sa from 398 nm to 29 nm. |
