Patent ID: 8895890

Claim:
A laser scribing installation for treatment of grain oriented magnetic sheets, as a strip advancing on a planar surface along a longitudinal direction of movement, said installation comprising a laser generator, a cylindrical telescopic optical group with varying focal distance for formation of an elliptic sectioned laser beam, and a rotating mirror scanner for scanning the laser beam according to a pre-defined angle, wherein said installation further comprises: a parabolic reflector extended transversally to the strip for receiving the laser beam from the rotating mirror scanner and focusing the beam on the strip, as a lengthened elliptic spot, along a treatment path; a limiting plate arranged between the strip and the parabolic reflector and defining a window for the laser beam directed to the treatment path, and a protection device for generating a gaseous lamina between the limiting plate and the strip, adjacent to the said window; wherein said laser beam defines, in an elliptic section, axes of varying ellipticity as function of said focal distance; wherein said telescopic optical group is adjustable for modifying the length of one of said axes of the laser beam incident on said strip; and wherein said gaseous lamina has function of gaseous barrier tangent to said window for protecting said parabolic reflector from contamination.