Patent ID: 8097830

Claim:
A method of processing an object of condensed substance using a laser comprising the steps of: (a) generating a laser pulse by means of a pulsed laser, wherein said laser pulse is negatively chirped such that it is spectrally dispersed with wavelengths running slower in the propagation medium forming a front flank of the laser pulse and wavelengths running faster forming the rear flank of the laser pulse; (b) emitting said laser pulse in the direction of said object; (c) focusing said laser pulse in time and space so that (c1) the peak of the laser pulse exceeds the crucial power for a Kerr-induced self-focusing effect of the laser pulse at a position remote from the laser and said object so that a filament is formed by the laser pulse, and (c2) the filament extends from said remote position through air at least to the surface of said object; and (d) causing evaporation or excitation to plasma of at least part of said object without re-adjusting the laser focus.