Femtosecond Laser Engraving of Deep Patterns in Steel and Sapphire

Abstract

Femtosecond laser engraving offers appealing advantages compared to regular laser engraving such as higher precision and versatility. In particular, the inscription of deep patterns exhibits an increasing interest in industry. In this work, an optimization protocol based on constraining overlap ratio and scan number is demonstrated. The proposed method allows changing overlap ratio while maintaining depth in the same range, which reduces the sampling number. This study WAS applied to stainless steel 316 L and sapphire for engravings deeper than 100 μm. Results exhibit overall depths higher than threshold values and allowed to determine optimized engraving quality, for instance, roughness in steel can be reduced while maintaining depth and taper angle by reducing overlap ratio. The optimized laser parameters such as roughness and taper angle factors for sapphire were also found to be as follows: 200 kHz, 86% overlap and 12 J/cm2. As a demonstration, a logo engraving is illustrated at the end.

Ultrafast Laser Patterning of Metals Commonly Used in Medical Industry: Surface Roughness Control with Energy Gradient Pulse Sequences

“…Rectangles with defined size (4 × 2 mm [ 44 ] for stainless steel, brass and silver, or 2 × 1 mm rectangle in the case of titanium) have been achieved with pulse overlap OL of 86% in both dimensions, following the optimum irradiation conditions for reduced roughness described in [ 44 ]. This corresponds to a spacing of , considering a scan speed of 36.4 mm/s and a pulse repetition rate of 10 kHz.…”

“…On each sample, three rectangular areas with different laser irradiation sequences and an identical amount of total deposited energy have been conducted. The laser pulse fluence of 5 J/cm 2 was chosen based on a previous study [ 44 ], where it was shown to be a good compromise between easy implementation, high throughput and relatively low surface roughness after the laser process. This value was also chosen in this way for the gradient study.…”

Femtosecond Laser Fabrication of Curved Plasma Channels with Low Surface Roughness and High Circularity for Multistage Laser-Wakefield Accelerators

“…Electronic excitation can be used to optically control the phase transition of solid materials. Excitation of approximately 10% of valence electrons results in the transition from The inescapable consequence of the overlap rate on the processed surface is a matter of grave concern [24,25]. To understand the exact effect of certain parameters and avoid complications, the point density (number of processed points per millimeter length) is adjusted to control the overlap rate of the laser pulse.…”

Ultrafast Cylindrical Vector Beams for Improved Energy Feedthrough and Low Roughness Surface Ablation of Metals

“…where kx is the number of pulses per line and ky is the number of lines. An overlap ratio of φ = 0.7 has been chosen as based on previous studies of process optimization using Gaussian laser beams [18]. Applying Equation ( 4), N e f f G = 4.36.…”