Apparatus for dynamic surface annealing of a semiconductor wafer includes a source of laser radiation emitting at a laser wavelength and comprising an array of lasers arranged in rows and columns, the optical power of each the laser being individual adjustable and optics for focusing the radiation from the array of lasers into a narrow line beam in a workpiece plane corresponding to a workpiece surface, whereby the optics images respective columns of the laser array onto respective sections of the narrow line beam. A pyrometer sensor is provided that is sensitive to a pyrometer wavelength. An optical element in an optical path of the optics is tuned to divert radiation emanating from the workpiece plane to the pyrometry sensor. As a result, the optics images each of the respective section of the narrow line beam onto a corresponding portion of the pyrometer sensor. The apparatus further includes a controller responsive to the pyrometry sensor and coupled to adjust individual optical outputs of respective columns of the laser array in accordance with outputs of corresponding portions of the pyrometry sensor.