摘要：

A projection lens and a source of exposure light are employed for projecting an image of a reticle onto a first reference mark or a semiconductive wafer, both of which are movably supported in the image plane of the projection lens. Optical apparatus, including a source of nonexposure light and the projection lens, is provided for imaging a second adjustable reference mark onto the first reference mark or the semiconductive wafer to facilitate use of the projection lens in aligning a semiconductive wafer covered with a photoresist opaque to exposure light.

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