Ultrashort laser processing of glass : cutting and micro surface structuring of soda-lime glass

Groendijk, H.A. (2016) Ultrashort laser processing of glass : cutting and micro surface structuring of soda-lime glass.

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Abstract:Ultrafast laser processing of glass has been a hot topic over the last decade. In this report, a femtosecond laser setup with an average power output of only 3.2 W will be used for cutting and surface structuring of soda-lime glass. The objective of this research is to get in-house knowledge about both the laser glass cutting and laser surface structuring of glass, this includes finding laser parameters and typical achievable results. Cutting of glass is done by combining two existing and proven cutting methods, namely controlled fracture propagation and elongated spot cutting. Optimal cutting parameters are discovered for cutting figures of different shapes and sizes. Squares and circles between 5 and 20 mm can be created from a sample with a 26 mm width, more complex shapes like stars are hard to create due to random cracking, shortcutting and not reaching the tensile stress threshold. Surface structuring is done by surface laser modification with a subsequent selective etching step using hydrofluoric acid as etchant. The influence of the laser and etching parameters on the resulting glass structures is investigated, namely groove depth increases sharply with laser power at a specific threshold and decreases almost linearly with laser scanning speed. The oscillation amplitude decreases with increasing scanning depth and multiple pathing, although multiple pathing also decreases the depth consistency. Mostly grooves of a couple of µm are created and combined to symmetrical grating structures. Typical grating structures have a width/depth ratio between 5 and 10 and the smallest achievable grating had grooves with a width of 3.9 µm and a depth of 0.56 µm. Using a bigger beam radius at the beam focus of the laser grooves with a flat bottom surface can be created. It is also possible to combine two of these structures together created a stepwise channel depth. A larger flat bottom surface can be achieved by combining an arbitrary amount of scanning paths spaced closely together, although some height variation is still present.
Item Type:Internship Report (Master)
Clients:
Institute of Photonic Technologies, Germany
Faculty:ET: Engineering Technology
Subject:52 mechanical engineering
Programme:Sustainable Energy Technology MSc (60443)
Link to this item:http://purl.utwente.nl/essays/71983
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