The process of laser filament cutting produces a practical nongap cut which ensures high precision in lateral dimensions at the micrometer scale. Commercially available OptiWhite soda lime silicate glass is filamented using a 1064 nm picosecond pulsed Nd:YAG laser with varying burst energies and focus positions. The filaments are characterized perpendicular to the incident laser beam using scanning electron microscopy (SEM). Maximum roughness Rz evaluated with laser scanning microscopy is measured on the cut sides. The characteristic mechanical strength σ of glass cleavage is decreased by a factor of 6 with the presence of the filaments. This σ obtained in the four‐point‐bending setup decreases with the increase in energy deposited in the material by the laser. It is found that the cleaving cracks are guided by the filament only if the network of microcracks is sufficiently developed. A threshold of the cleaving guidance is linked to a critical surface modification width of 2.5 μm which corresponds to half the distance between filaments. The influences of the laser parameters, sample thickness, and sample position in respect of the focal plane on the cut quality are studied. Guidelines are given to define a suitable parameter set.

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Utilizing ultra-short-pulse laser filamentation of glass is one of the latest developed techniques to cut glass. In comparison with other techniques the superior benefits are a small heat-affected zone, a quasi-non-gap cut, and the possibility to free from cut. However, despite the large interest in the laser/glass interaction for various laser sources and pulse durations, the process of cleaving and the underlying mechanisms are fairly undescribed. In this study, we utilized a Nd:YAG laser with an average power of 100 W, a center wavelength of 1,064 nm, and a pulse duration of 12 ps via a specially designed optic to generate laser filamentation in soda-lime- and borosilicate glass with varying Pitch and Burst parameters. The filaments and cut edge are analyzed with scanning electron- and laser scanning microscopy to study the topological phenomena and roughness. Photoelastic measurements were done to assess the stress distribution within the glass and show cumulative interactions at the filament extremity. From the observations made, phenomenological models are proposed to describe the initial micro crack formation considering the shock wave and thermal influence caused by the laser pulses. Two types of micro cracks are identified, with radial cracks passing through the filament and bypass cracks that form around the laser-affected zone. Models are elaborated for both glass types to evaluate the influence of a parameter change on the micro crack formation and the cleaving guidance. The different behavior between soda-lime- and borosilicate glass, with their distinct physical properties, helps to interpret the influence of laser parameters on the micro crack formation and the cleaving guidance.

Over the past decade, glass has become an increasingly sophisticated structural and functional component in uses as varied as flat panel displays, automobiles and architecture. For the manufacturer, this has created a drive to enhance the physical characteristics of the glass itself, to develop more advanced coatings, and also to improve the process for cutting glass in terms of higher precision, greater speed, reduced environmental impact, and lower cost.