Effects of Spherical Aberrations on Micro Welding of Glass using Ultra Short Laser Pulses

In micro-welding of glass by means of ultra-short laser pulses focusing objective lenses with a high numerical aperture are necessary to generate plasma by nonlinear processes. However, due to the strong focus through the plane surface of the glass samples strong spherical aberrations occur, which increase the necessary power to start the nonlinear absorption processes. The influence of the spherical aberrations on the shape of the molten zone, on the pulse energy necessary for plasma generation is studied experimentally in the present work.