independently of one another with the aid of known measurement methods in this case care should be taken to simulate the installation situation of the optical elements in the projection lens 6 as precisely as possible during this independent analysis so as to prevent the installation of the optical elements in the projection exposure system 1 from giving rise to additional perturbation contributions which impair the optimisation of the imaging properties of the projection lens 6 the determination of the birefringence contributions may for example comprise determination of the position of the crystal axes of the optical elements to be analysed when crystalline materials are involved the measurement results are evaluated by the computer 14 it determines the respective perturbation contributions of the individual optical elements of the projection lens and assigns these contributions to the individual polarization dependent and polarization independent perturbations the computer 14 subsequently calculates and optimises a target function merit function this target function takes in the dependencies of the perturbation contributions of all the optical elements on the degrees of freedom in movement of these optical elements rotation inclination centring in the exemplary embodiment which is represented this calculation is carried out for the optical components 9 and 10 as was mentioned above the lens 9 is rotatable relative to the optical plate 10 about.