Effect of retrace error on stitching coherent scanning interferometry measurements of freeform optics

We report on the effect of retrace error during measurement freeform optics using a commercial coherence scanning interferometer (CSI), and its in-built stitching capabilities. It is shown that measuring segments under non-null conditions, results in artifacts measured zone, similar to Seidel aberrations. An experimental approach used quantify induced aberrations based local slopes surface. Simulation surfaces containing different order have significant data. A correction method proposed uses measurements determine required slope position aperture. These corrections reduce difference from comparison Fizeau interferometer.