A dual setup composed of a point diffraction interferometer (PDI) and a Hartmann–Shack (HS) wavefrontsensor was built to compare the estimates of wavefront aberrations provided by the two different andcomplementary techniques when applied to different phase plates. Results show that under the sameexperimental and fitting conditions both techniques provide similar information concerning the wavefrontaberration map. When taking into account all Zernike terms up to 6th order, the maximum differencein root-mean-square wavefront error was 0:08 μm, and this reduced up to 0:03 μm when excludinglower-order terms. The effects of the pupil size and the order of the Zernike expansion used to reconstructthe wavefront were evaluated. The combination of the two techniques can accurately measure complicatedphase profiles, combining the robustness of the HS and the higher resolution and dynamic range ofthe PDI.

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