Abstract: A mark detecting device usable in an alignment and exposure apparatus for aligning an alignment mark of a mask with an alignment mark of a wafer and for exposing a resist layer provided on the surface of the wafer to a pattern of the mask with radiation.

Abstract: An exposure control device of a copying machine is provided with a white member at an end portion of an original document holding surface of a platen so as to prevent adhesion of toners to a top end portion of the copying paper. While a scanning optical system moves from the scan start point to the border between the original document and the white member, sufficient light quantity to prevent fogging of the image of the white member is supplied by the exposure lamp. The light quantity of the exposure lamp is changed to a suitable value corresponding to the original document in response to a signal for detecting the border.