| CPC G03F 7/70266 (2013.01) [G02B 13/16 (2013.01); G02B 26/0825 (2013.01); G03F 7/70891 (2013.01); H10N 30/206 (2023.02); H10N 30/802 (2023.02)] | 20 Claims |

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1. An apparatus, comprising:
a projection objective, comprising:
an optical device;
a controller; and
temperature sensors,
wherein:
the optical device comprises an optical element and an electrostrictive actuator;
the optical element comprises an optically effective surface;
the optical element is adjacent an intermediate image plane of the apparatus;
the controller is configured to provide a control voltage to the electrostrictive actuator to deform the electrostrictive actuator;
the electrostrictive actuator is connected to the optical element to influence a surface shape of the optically effective surface;
the temperature sensors are configured to measure: a) a temperature of the electrostrictive actuator; b) a temperature change of the electrostrictive actuator; c) a temperature distribution of the electrostrictive actuator; d) and/or a temperature distribution of surroundings of the electrostrictive actuator;
the temperature sensors are configured so that, at least at times when the electrostrictive actuator influences the optically effective surface of the optical element, the temperature sensors determine: a) the temperature of the electrostrictive actuator; b) the temperature change of the electrostrictive actuator; and/or c) a temperature of the surroundings the electrostrictive actuator, thereby taking account of a temperature-dependent influence when the electrostrictive actuator is driven by the control device; and
the apparatus is a projection exposure apparatus.
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