Anisotropic stress generation in borosilicate glass by nanosecond excimer laser irradiation for figure correction

Pulsed UV laser irradiation of glass leads to stress in the near surface material. The introduction of such stresses by nanosecond-pulsed lasers at fluences in the melting regime is based on the temperature gradient mechanism. The material at the surface melts, expands and contracts during solidification, resulting in tensile stress. This stress influences the shape (local curvature) of the glass sheet. By line-patterned irradiation with periods of about 10 µm, strongly anisotropic curvatures indicating anisotropic stress can be induced. With suitable utilization of these stress states, the induced macroscopic deformations can be used in the future for figure correction to obtain high precision optics or even for manufacturing freeform-optics.