Mirror system, method for operating a mirror system, projection lens for a microlithographic projection exposure system, and computer program product

A mirror system, comprising:

• an EUV mirror comprising a mirror body and an optical surface supported by the mirror body;
• a temperature sensor;
• a control unit;
• and
• a temperature-control module,
• wherein:
• the temperature sensor is configured to determine a temperature value of the mirror body;
• the temperature sensor is configured to transmit the temperature value of the mirror body to the control unit;
• the control unit is configured to determine control commands for the temperature-control module;
• the temperature-control module is actuatable by the control commands so that the temperature-control module influences a temperature of the mirror body;
• in a first operating state of the mirror system, the control unit is configured to determine the control commands based the temperature value of the mirror body and a first temperature setpoint value for the temperature of the mirror body;
• in a second operating state of the mirror system, the control unit is configured to determine the control commands based the temperature value of the mirror body and a second temperature setpoint value for the temperature of the mirror body;
• the first operating state is different from the second operating state;
• and
• the first setpoint value is different from the second setpoint value.