INDIRECT PULSED LASER MACHINING METHOD OF TRANSPARENT MATERIALS BY BRINGING A ABSORBING LAYER ON THE BACKSIDE OF THE MATERIAL TO BE MACHINED

摘要

The present invention relates to a novel indirect pulsed laser machining process of a transparent material. The process according to the invention comprises the steps of bringing a transparent material (12), at least in a region (19) thereof to be machined, into coupling with an absorbing layer (18), said coupling ensuring intense heat exchange; directing a laser pulse of a laser light (20) emitted by a laser source (10) through the transparent material (12) into the absorbing layer (18); having the energy of the laser pulse absorbed within a portion of the absorbing layer (18) located in the vicinity of the transparent material's region (19) to be machined, and thereby heating up said absorbing portion of the absorbing layer (18) to boiling and removing mechanically material from the region (19) to be machined through a retroaction exerted on said region (19) by the boiling-away material of the absorbing layer (18), comprising (i) applying as the transparent material (12) such a material that is essentially fully transmissive at the wavelength of the laser light (20), (ii) making the absorbing layer (18) of such a material that is essentially fully absorbing at the wavelength of the laser light (20), (iii) setting the energy of the laser pulse so as to correspond to at least the transparent material's (12) threshold fluence value for etching, and (iv) forming the absorbing layer (18) with such a thickness that ensures boiling away of the absorbing layer (18) in its full thickness at the transparent material's region (19) to be machined as a consequence of absorbing the energy of the laser pulse by it.