Aberration-Matched Filter for the Topological Vortex Charge Analysis
It is well-known that the astigmatic transformation is used to analyze the topological vortex charge. In this paper, a multi-order filter matched to various aberrations described by the Zernike polynomials is used to implement the astigmatic transformations of vortex beams. Such a filter makes it possible to simultaneously introduce several wave aberrations with various types and levels into the analyzed vortex beam in order to implement various aberrational transformations, including astigmatism. In this case, a set of aberration-transformed distributions of the analyzed vortex beam is formed in the focal plane in different diffracting orders that facilitates determination of its topological charge.