Exposure apparatus and measuring device for a projection lens

An optical system, comprising:

• an illumination system configured to generate projection light;
• a projection lens configured to image a mask on a photosensitive layer;
• an outlet configured to supply an immersion liquid so that immersion liquid that flows out of the outlet becomes in direct contact with the projection lens and the photosensitive layer to form a boundary surface to a surrounding gas;
• a heat transfer element configured to transfer an amount of heat to or from the immersion liquid;
• and
• a control device configured to adjust the amount of heat transferred by the heat transfer element to or from the portion of the immersion liquid,
• wherein the optical system is a microlithographic projection exposure apparatus.

An optical system, comprising:

• an illumination system configured to generate projection light;
• a projection lens configured to image a mask on a photosensitive layer;
• a plurality of outlets configured to supply an immersion liquid such that immersion liquid that flows out of the plurality of outlets becomes in direct contact with the projection lens and the photosensitive layer to form a boundary surface to a surrounding gas;
• and
• a control device configured to adjust the temperature of the immersion liquid that flows out of the outlets individually for at least two of the plurality of outlets,
• wherein the optical system is a microlithographic projection exposure apparatus.