Improvements in ultra-high precision surface structuring using synchronized galvo or polygon scanner with a laser system in MOPA arrangement

Abstract

In earlier work the capabilities of synchronizing a galvo scanner or a polygon line scanner with a picosecond laser system in MOPA arrangement were presented. However these systems only enabled precise positioning of laser pulses on the target relatively to each other. Since then a novel approach to increase the absolute precision in positioning has been developed. This improvement enables new and more efficient process strategies such as bidirectional processing or high precision structuring of large areas in combination with additional mechanical axes. These improvements represent a major step towards large scale industrial applications in laser based micromachining.

Radial scanning strategies leading to substantial improvements in processing time

“…For example, the pulse energy can be increased. However, publications 1 show that the optimal pulse energy depends on the spot radius and the threshold fluence of the material to be processed. Another approach is to change the deflection of the laser beam, such as increasing the pulse-to-pulse distance.…”

“…There are various strategies for marking a surface, each with their own advantages and disadvantages. One traditional method is using a synchronized system with a linear scanning strategy 1,2 , which involves scanning the laser horizontally across the workpiece and gradually increasing the vertical position. This strategy is simple to implement as it can be done using a cartesian coordinate system and it is easy to imagine the positions being approached.…”

Micromachining of Invar Foils with GHz, MHz and kHz Femtosecond Burst Modes

“…This outcome stems from the fundamental properties of light-matter interaction and cannot be easily overcome. Though the quality of the micromachined samples may be improved by increasing the spatial separation (decreasing pulse overlap), this requires using high-speed (10-100 m/s) translation systems, which are either specially modified galvo-scanner setups or polygon scanners [16]. This setup presents several drawbacks: implementation of sharp focusing in the system becomes complicated, and loss of working area cannot be avoided.…”

Throughput scaling by spatial beam shaping and dynamic focusing

“…A galvo scanner system allows flexible 2D beam positioning for random access and raster scanning without the requirement of additional axis, as indicated in figure 1a 9 . In figure 1b, a polygon scanner based solution is shown 8,10 , in figure 1c a helical processing by fast rotating cylinder 10 , both combined with additional obligatory positioning device. As indicated in figure 1d, an additional deflector, e.g.…”

“…1b) or galvo scanner systems in raster scanning mode (Fig. 1a) may offer sufficient speed but realization results in challenges to achieve adequate accurate positioning of the desired huge number of addressable spots at high processing speed 8,9,10 . Another raster based approach is helical processing on the surface of a rotating cylinder (Fig.…”