Abstract: A method of heating a selected portion of an object includes the steps of projecting an energy beam onto a surface of the object and repetitively scanning the beam in accordance with a scanning pattern so as to establish an effective spot on the surface, and displacing the effective spot along a track to progressively heat a selected portion of the object. The selected portion has a first width at a first position along the track and a second width at a second position along the track. The second width is less than 75% of the first width. The scanning pattern is repeated with a first frequency in correspondence with the first position and with a second frequency in correspondence with the second position, the second frequency being more than 60% and less than 140% of the first frequency.