Correcting light intensity for photolithography may include irradiating light having a first light intensity distribution through a photo mask having a mask pattern to a photosensitive layer on a wafer to form a first pattern corresponding to the mask pattern. A distribution of critical dimensions of the first pattern corresponding to the mask pattern may be determined, and a second light intensity distribution may be determined based on a relation between the first light intensity distribution and the distribution of critical dimensions of the first pattern. Then, light having the second light intensity distribution may be irradiated. Related systems are also discussed.