Measuring method and measuring system for interferometrically measuring the imaging quality of an optical imaging system

The imaging quality of an optical imaging system is interferometrically measured. A wavefront measurement has a first imaging scale β1 in a first direction and a second imaging scale β2 in a second, perpendicular direction. The second imaging scale differs from the first imaging scale by a scale ratio (β1/β2)≠1 (anamorphic imaging system). A first measurement structure (MS1) on a first structure carrier arranged on the object side of the imaging system has a two-dimensional mask structure suitable for shaping the coherence of measurement radiation. A second measurement structure (MS2) on a second structure carrier arranged on the image side of the imaging system has a diffraction grating. The first and second measurement structures are mutually adapted, taking account of the scale ratio so that an interference pattern arises upon imaging the first measurement structure onto the second measurement structure using the anamorphic imaging system.