Glass cutting optimization with pump-probe microscopy and Bessel beam profiles

摘要

The processing of transparent materials by ultrashort pulses has opened diverse promising and fast-growing application areas such as the cutting of glasses for consumer electronics. One of the major benefits is the precise energy deposition, which may result in local weakening of the glass and hence defines a preferential direction for the separation path. Due to the vast variety of possible uses for different displays, research in this field is needed for more complex shapes and glasses of various thicknesses. Bessel-Gaussian beams with their elongated, thin focus profile and self-healing nature are an excellent fit, even for glasses up to several millimeters. Additional development to more complex beam profiles allows precise tailoring with respect to the mandatory specifications of the cutting process such as process speed or the realization of inner contours. One concept for the latter is the use of tilted Bessel-Gaussian beams to achieve both high quality and easy separation. Further approaches include the usage of higher-order Bessel beams or modified Gauss-Bessel beams. We employ digital holographic techniques to create the various profiles with the desired absorption distribution. Traditional microscopes fail to characterize these sensible changes in the interaction region, since they are limited to visualize permanent changes (ex situ) of the glass structure only. We take advantage of pump-probe microscopy to receive concise recordings of the extinction mechanisms of the beam-material-interaction. With both, high temporal and spatial resolution of in-situ diagnostics we gain access to the entire process window which enables us to develop optimized processing parameters for high-quality glass cuttings.