The present invention relates to an optical unit, particularly for micro-lithography, comprising an optical module, a support structure und a force-generating device. The force-generating device is connected to the optical module and the support structure and is designed to exert a force on the optical module. The force-generating device comprises a fluid force-generating element having a working chamber that can be subjected to a working fluid having a working pressure. The force-generating element is designed as a muscle element, exerting a first tensile force at a first working pressure and exerting a second tensile force that is higher than the first tensile force at a second working pressure that is higher than the first working pressure.