Characterization of a hybrid scanning system comprising acousto-optical deflectors and galvanometer scanners

Abstract

We report on the characterization of a hybrid laser scanning system using acousto-optical deflectors in combination with galvanometer scanners for ultra-short pulse laser material processing. The hybrid scanning system is characterized by the roundness of static pulsed ablations of metal thin film on a transparent substrate within the acousto-optical scanning field at different galvanometer scanner deflection angles and laser focal positions. An ablation roundness of more than 90% is reached in a defocusing range of 200 $$\upmu \text{m}$$ μ m within a galvanometer scanfield of 900 $$\text{mm}^2$$ mm 2 , corresponding to approximately 74% of the usable scan area of the f-theta lens. A high maximum positioning speed of 843 m/s is pointed out within an acousto-optical scanfield of 0.4 $$\text{mm}^{2}$$ mm 2 by applying positioning frequencies of up to 1 MHz across a distance of 843 $$\upmu \text{m}$$ μ m . Consequently, the hybrid scanning system combines the advantages of optical and mirror-based scanners, enabling a highly dynamic and extremely precise laser beam positioning in a large processing area.

Acousto-optic Scanning Spatial-switching Multiphoton Lithography

“…The deflected beams have an aberration-free wavefront due to a non-linear swept signal being used to drive the AOD y . When the AOD y is driven by a non-linear signal, the wavefront of the deflected laser is significantly different from the linear swept signal which was widely used in the past [45][46][47][48]. The comparison of the wavefront while AOD y is driven by 'non-linear swept' and the 'linear swept' is shown in figure 1(b).…”

Green nanoparticle synthesis at scale: a perspective on overcoming the limits of pulsed laser ablation in liquids for high-throughput production

“…This effect is more pronounced for small processing patterns, requiring large patterns with lower spatial resolution than the galvanometric scanners. 148 Streubel et al (2016) 74 proposed for the first time the employment of a unidimensional polygon scanner (500 m s À1 ) together with a galvanometric scanner to achieve a 2D scanning of the target sample (Fig. 9a).…”

“…The galvanometer scanners are based on the mirror(s) revolved with rotary motor(s) that deflect the input beam into a designed pattern with micrometric precision. 148 This working principle limits the maximum speed that can be achieved by this technology due to the inertia from the mass of the mirror(s) and other moving parts. 149 The fastest reachable speed of a galvanometer scanner is less than 200 rad s −1 .…”

Ultrafast Laser Additive Manufacturing: A Review

“…The diameter of the deposited dots is in the hundreds of nanometres, the number of which depends on the laser parameters. Recent work to further improve scanning speeds includes acousto-optical deflectors that are not limited by scanning mirror inertia, as incorporated in a hybrid system in [255]. Such systems, although more complicated, may fulfill industrial needs if quality consistency can be maintained.…”