Provided are methods and apparatus for exposing multiple substrates within a single exposing apparatus using only a single light source wherein a first substrate is exposed in a series of steps or shots during which light transmitted along a primary optical path is directed onto a primary surface of the substrate with the substrate being repositioned between sequential shots. A second substrate is exposed during the period of time while the first substrate is being repositioned by altering the optical path to divert the light from the light source into a secondary optical path that will expose a region on the second substrate. When the first substrate has been repositioned, the diversion of the light is terminated so that the light will again be transmitted along the primary optical path in order to expose the next sequential shot on the primary surface of the first substrate.