Method for improving the imaging properties of a projection objective, and such a projection objective

A system, comprising:

• a microlithography projection objective, comprising:
• a plurality of lenses that are arranged between an object plane of the microlithography projection objective and an image plane of the microlithography projection objective, the plurality of lenses including a first lens and a second lens;
• a first manipulator configured to actively deform the first lens;
• and
• a second manipulator configured to actively deform the second,
• wherein when the first lens and the second lens are deformed during use of the microlithography projection objective:
• a) a radially primary Zernike order of an image defect is corrected substantially independently of a radially higher Zernike order of the image defect;
• or
• b) the radially higher Zernike order of the image defect is corrected substantially independently of the radially primary Zernike order of the image defect.