Optimized Strategies for Seamless Stitching with Synchronized Galvo Scanner and Linear Axis

Laser surface texturing using ultra short pulsed lasers in combination with galvo scanners is limited to the scan field of the galvo scanner which is typically 65x65 mm using a 160 mm objective. By combine the galvo scanner with an additional high precision linear axis, it is possible to enhance the working field. Increased surface roughness and visible seams in the intersection region have to be avoided to preserve the high quality achieved by using ultra short pulsed laser systems. Strategies to minimize this influence are developed by using a system with a synchronized galvo scanner and by working with b/w bitmaps in a raster scanning mode. This allows splitting an image into two sub-images and compare different strategies for its recombination on the sample. For these tests always the whole image is scanned but with laser switched off alternating for the left and the right sub-image. This setup offers the possibility to evaluate different stitching strategies for the combination of two sub-images without influence of the exact alignment of the linear axis to the galvo scanner. Transferring the stitching strategy to a system including one or two linear axes needs a perfect alignment of the two coordinate systems to preserve the high accuracy. Therefore, a solution for aligning the two coordinate systems with highest accuracy will be presented as well.