Systems and methods for forming a time-averaged line image having a relatively high amount of intensity uniformity along its length is disclosed. The method includes forming at an image plane a line image having a first amount of intensity non-uniformity in a long-axis direction and forming a secondary image that at least partially overlaps the primary image. The method also includes scanning the secondary image over at least a portion of the primary image and in the long-axis direction according to a scan profile to form a time-average modified line image having a second amount of intensity non-uniformity in the long-axis direction that is less than the first amount. For laser annealing a semiconductor wafer, the amount of line-image overlap for adjacent scans of a wafer scan path is substantially reduced, thereby increasing wafer throughput.