Abstract: A measuring device for measuring structures on a transparent substrate includes an incident-light illuminating device, an imaging device, and a detector device for the imaged structures and a measuring stage for receiving the substrate. The stage is displaceable in an interferometrically measurable fashion perpendicularly to and relative to an optical axis of the imaging device. The measuring stage is designed as an open frame with a receiving edge for the substrate. A transmitted-light illuminating device is provided beneath the measuring stage. The optical axis of the transmitted light illuminating device is aligned with that of the incident-light illuminating device.

Abstract: A method is provided for measuring structures on a mask surface in which the mask is supported on a measuring stage that is interferometrically measurably displaceable perpendicularly to an optical axis of an image-measuring system. A mask coordinate system associated with the mask is aligned using alignment marks relative to a measuring device coordinate system. With set positions of the structures in the mask coordinate system being specified in advance, the positions of at least two external edges of the mask in the mask coordinate system that are perpendicular to one another are measured in addition to the actual positions of the structures in the mask coordinate system.