Catadioptric projection objective including a reflective optical component and a measuring device

A projection objective configured to image an object field onto an image field via imaging radiation, the projection objective comprising:

• a reflective optical component;
• a measuring device;
• and
• a deformable optical element,
• wherein the projection objective is a catadioptric projection objective, and
• wherein during use of the projection objective:
• the reflective optical component reflects a first part of the imaging radiation;
• the reflective optical component transmits a second part of the imaging radiation;
• the reflected, first part of the imaging radiation at least partly contributes to imaging of the object field into the image field;
• the transmitted, second part of the imaging radiation is at least partly fed to the measuring device;
• the transmitted, second part of the imaging radiation is less than 10% of the imaging radiation impinging on the reflective optical component;
• and
• the deformable optical element corrects an imaging quality of the projection objective.