Abstract: An exposure apparatus for exposing a photomask pattern onto a photosensitive substrate via a plurality of optical systems includes a source of illumination for irradiating the photomask pattern with beams of light adapted to pass through the pattern and optical systems onto the substrate. A scanning mechanism for synchronously scanning the photomask pattern with the beams of light is included to transfer the pattern to the substrate. A plurality of illumination intensity measuring devices is provided for substantially simultaneously measuring the illumination intensities of the beams of light passing through the optical systems.

Abstract: A scanning type exposure apparatus comprises a mask stage RST for scanning a mask R across an illumination area on the mask R, a projection optical system PL for projecting an image of a pattern on the mask R onto a photosensitive substrate W, and a substrate stage WST for scanning the photosensitive substrate W across an exposure area. The apparatus comprises an image pickup unit 53 having its light-receiving section 1 provided on the substrate stage WST, for photoelectrically detecting an image of a mark pattern on the mask R, and a combining unit 4 for combining signals outputted from the image pickup unit 53 during a period in which the light-receiving section is scanned across the exposure area in synchronization with scanning for the mark pattern across the illumination area. Image formation characteristics or a position of the image of the mark pattern is determined on the basis of an output of the combining unit 4, which may be corrected before actual exposure.