A scan type exposure apparatus wherein a pattern of an original is lithographically
transferred to a substrate sequentially while the original and the substrate are
scanningly moved relative to exposure light, the apparatus including a photodetector
disposed at a position optically conjugate with the original, and a storing device
for storing correction information with respect to an output of the photodetector,
in relation to different positions of the original to be illuminated with the exposure
light, such that, in the lithographic pattern transfer, the output of the photodetector
can be corrected by use of the correction information.
