Abstract: Systems, apparatuses, and methods are provided for adjusting illumination slit uniformity in a lithographic apparatus. An example method can include determining whether an exposure field for a wafer exposure operation is less than a maximum exposure field of a uniformity correction system. In response to determining that the exposure field is less than the maximum exposure field, the example method can include modifying illumination slit uniformity calibration data associated with the maximum exposure field to generate modified illumination slit uniformity calibration data associated with the exposure field. Subsequently, the example method can include determining an optimal position of a finger assembly of the uniformity correction system based on the modified illumination slit uniformity calibration data.