An optical element for correcting aberrations in an optical apparatus has
a casing. The casing is filled with liquid and has a support layer and a
cover layer designed to pass light of a predetermined wavelength range.
The casing accommodates several actuators. Each actuator has a first end
supporting the cover layer and a second end supporting the support layer.
Each actuator is able to locally change a local distance between the
support layer and the cover layer to correct for local aberrations in a
light beam directed to the optical element by providing local phase
shifts. The optical element may be used in a lithographic apparatus.