Patent ID: 7977651

Claim:
An objective having an optical axis, an object plane and an image plane, the projection objective comprising: a total of six mirrors, each of the six mirrors being arranged along the optical axis of the objective and configured so that during operation of the system the six mirrors direct radiation along a path from the object plane of the objective to the image plane of the objective to form in the image plane an image of an object positioned at the object plane, wherein: the path from the object plane of the objective to the image plane of the objective is characterized by a plurality of chief rays, during use of the objective, each of the plurality of chief rays diverges from the optical axis of the objective; a first mirror of the six mirrors along the path from the object plane of the objective to the image plane of the objective is between the image plane of the objective and a sixth mirror of the six mirrors along the path from the object plane of the objective to the image plane of the objective; and the objective is a projection objective configured to be used in a microlithography projection exposure apparatus.