Evaluation of scanner-based focus finding methods on rough surfaces
Cvecek K, Eckl J, Eiselen S, Huber HP, Schmidt M (2015)
Publication Type: Journal article
Publication year: 2015
Journal
Book Volume: 10
Pages Range: 304-309
Journal Issue: 3
DOI: 10.2961/jlmn.2015.03.0012
Abstract
Automated laser beam focus positioning for precise work piece alignment is highly important in laser processing. Ideally, the laser used for processing of the work piece should also be used for focus finding. For this a confocal camera can be used in front of a galvanometric scanner and objective. However, in typical laser processing applications the roughness of the sample in combination with the laser spot size and the coherence of the laser provide a confocal camera image with a distinct speckle pattern. This speckle pattern can impede the determination of the focal position with respect to the work piece, especially if simple evaluation algorithms are applied. In this work we investigate the performance of several more advanced image evaluation methods on confocal camera images for work pieces of different materials, different roughness under normal and tilted incidence of the laser beam. We show that two investigated algorithms provide a positioning uncertainty that is well below the Rayleigh length of the laser beam.
Authors with CRIS profile
Kristian Cvecek
Lehrstuhl für Photonische Technologien
Michael Schmidt
Lehrstuhl für Photonische Technologien
Additional Organisation(s)
Involved external institutions
Germany (DE)How to cite
APA:
Cvecek, K., Eckl, J., Eiselen, S., Huber, H.P., & Schmidt, M. (2015). Evaluation of scanner-based focus finding methods on rough surfaces. Journal of Laser Micro Nanoengineering, 10(3), 304-309. https://dx.doi.org/10.2961/jlmn.2015.03.0012
MLA:
Cvecek, Kristian, et al. "Evaluation of scanner-based focus finding methods on rough surfaces." Journal of Laser Micro Nanoengineering 10.3 (2015): 304-309.
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