a suitable spot diameter configured for the beam shaper 115 the beam shaper 115 then distributes the irradiance of the expanded collimated beam 113 so that the flattened collimated beam 121 has a uniform irradiance profile the aspherical lenses 117 119 of the beam shaper 115 may be fabricated from micro lens or using holographic techniques by shaping surface profiles of the aspherical lenses 117 119 accordingly a desired refractive index that ensures controlled phase distribution of electromagnetic waves within an operating range of wavelength can be configured in particular the beam shaper 115 distributes the irradiance of the expanded collimated beam 113 by first converging it with predetermined aberration characteristics through the aspherical lens 117 and subsequently diverging the collimated beam 113 with the aspherical lens 119 to collect the redistributed electromagnetic waves the second beam expander 123 modifies the aspect ratio of the flattened collimated beam 121 for optimum processing and thus higher throughput for cost effective manufacturing the combination of the lenses 109 111 117 119 125 127 also allows precise aberration control of the flattened collimated beam 121 with the modified aspect ratio within a desired spatial range the flattened collimated beam 121 with the modified aspect ratio is then reflected by the mirror 129 to the focusing lens assembly 131 which focuses the flattened laser output 133 on the semiconductor wafer 102 fig1 shows the flattened laser output 133 having a major longitudinal axis as well as a minor axis orthogonal to the major longitudinal axis in particular the flattened laser.