Damage-free laser micromarking of glass

Abstract

Unfortunately glass is highly transparent for the wavelength of 1.06 µm commonly used by marking systems. Absorption via nonlinear effects can circumvent this problem. There are three conditions for an effective use of nonlinear effects: high repetition rate (500 Hz), TEM00 beam quality (M^2 < 1.5) and high pulse power (>0.5 MW). Microplasma laser sputtering in particular allows marking of glass surfaces without any damage, i.e. without cracks and residual stress. Micromarking with a point distance of about 25 μm is possible. This is the equivalent of a printer resolution of 1000 dpi.