A Novel Two-Steps Approach for the Correction of 3-D Position Errors of the Measuring Probe in a Non-Redundant Spherical Scanning

This work deals with the correction of 3-D position errors of the scanning probe present in a non-redundant (NR) spherical near-field/far-field transformation (NF/FFT) technique. The here developed approach consists into two main steps. In the first one, the so called “spherical wave correction” technique is applied to compensate for the phase errors that alter the gathered NR voltage samples owing to their radial shifts from the measurement sphere. The so restored samples, now lying on the spherical surface but not in the exact locations fixed by the NR sampling on it, are then exploited to retrieve, using an ad-hoc iterative technique, the correctly placed ones. In the end, the so corrected samples are interpolated via an optimal sampling interpolation formula to obtain the data required to carry out the standard spherical NF/FFT technique.