Method and device for laser-assisted separation of a portion from a sheet glass element

A method for separating a portion from a sheet glass element, the method comprising:

• producing filamentary damages in a volume of the glass sheet element adjacently aligned along a non-rectilinear separation line, the non-rectilinear separation line dividing the sheet glass element into the portion and a remaining main part;
• causing thermal expansion and/or contraction so that the portion and the remaining main part change size differently from each other to produce local tensile stresses sufficient such that the portion detaches from the main part along the non-rectilinear separation line, wherein the portion and the remaining main part each remain intact as a whole;
• and
• coordinating an adjustment of L, ΔT, and α such that a minimal gap width (S) between the portion and the remaining main part is greater than a mean roughness (R), wherein L is a minimum extension of the portion in a plane of the glass sheet element, ΔT is a temperature difference in Kelvin between an average temperature of the remaining main part and an average temperature of the portion during the heating and/or cooling step, α is a coefficient of thermal expansion of the material of the glass sheet element, and R is an average roughness of an edge surface of the portion along which the portion separates from the remaining main part,
• wherein the step of producing the filamentary damages comprises:
• generating a plasma within the volume with laser pulses of an ultrashort pulse laser, wherein the sheet glass element comprises a material that is transparent to the laser pulses, and
• displacing points of incidence of the laser pulses over a surface of the glass sheet element along the non-rectilinear separation line.