Method of operating a microlithographic projection exposure apparatus

A method of operating a microlithographic projection exposure apparatus comprising a mask holder for holding a mask, a substrate holder for holding a substrate, a projection lens having several optical elements for imaging mask structures of the mask onto the substrate and a manipulator system, wherein the optical elements, the mask holder and the substrate holder each are an optical path element in an exposure optical path of the projection exposure apparatus and the manipulator system is configured for adjusting several travels, defined by travel variables, at the optical path elements of the projection lens, the method comprising:

• providing a wave front deviation of the projection lens, and
• determining a control command comprising travels for the manipulator system for correcting the wave front deviation using a model,
• wherein the model describes the wave front deviation as a function of the travel variables and comprises a group of offset coefficients, which are independent of the travel variables, a group of linear coefficients, which are each attributed to one of the travel variables to the power of one, and a group of quadratic coefficients, which are each attributed to a product of two of the travel variables or to a square of one of the travel variables, and
• wherein the offset coefficients are calibrated more frequently than are the linear coefficients.