A CO2 laser beam 12 is converted into a beam of uniform intensity at the position of a phase matching element 15 by an intensity converting element 14 and the phase matching element 15. Then, the uniform intensity beam irradiates a mask 17 containing an aperture variable in size via a variable-magnification...http://www.google.fr/patents/US6504652?utm_source=gb-gplus-shareBrevet US6504652 - Apparatus and method for laser processing
