Measurement method for interferometrically determining a surface shape

A method for designing phase gratings, comprising:

• generating a multiplicity of different designs of a phase grating, each of which is configured to generate a respective test wave from an input wave radiated onto the phase grating, based on specified boundary conditions,
• generating respective interferograms, corresponding respectively to the different designs, in a measurement arrangement by superimposing the test wave assigned to the respective design with a reference wave which has been reflected by a reference element;
• determining positions of disturbance points for each of the generated designs that are contained in interferograms corresponding respectively to the different designs,
• identifying disturbance points in mutually same positions in the interferograms of, in each case, at least two of the generated designs, wherein the disturbance points are each caused by three wave superposition of the test wave, the reference wave and a disturbance wave, wherein the disturbance wave is generated at a disturbance starting point of the respective phase grating and differs from the test wave at the disturbance starting point in wavefront and/or propagation direction, and
• selecting a combination of at least two of the generated designs, taking into account an identified number of the disturbance points in the mutually same positions in comparison with other combinations of the generated designs.