Results of Zernike fit to the height difference values of position sweeps of simulated data for different specimens. (a) Zernike coefficients for an asphere moved along the optical axis. (b) Defocus-coefficient (Z₄) for four different specimens over axial position. (c) Zernike coefficients for an apshere moved laterally. (d) Primary x-Coma for different specimens over lateral position.