A robust characterization procedure of the focus drift during the lens heating effect is introduced. Through the optimized lens heating factors, we could keep the better wafer image control when exposure. Result in better critical dimension uniformity across wafer and across one field. This paper will present a detailed optimization procedure for lens heating and the benefit to fix the edge and alterative yield loss. There are several methods to characterize the total focus drift during exposure and how to keep the best focus of the image to the center of the focal plan deviation to get the more better image printing control. These methods including the image sensor scan, measurement the alignment offset of the focal mark, exposure-defocus window and CD measurement. The focus drift could be exactly compensated base on the different saturated data and keep the BF in the center of the FPD.