  In this work, we propose and demonstrate experimentally a new family of
vector beams, the Helico-Conical Vector Beams (HCVB), whose spatial degree of
freedom is encoded in the Helico-Conical Optical Beams. We use Stokes
polarimetry to study their properties and find that upon propagation their
transverse polarisation distribution evolves from non-homogeneous to
quasi-homogeneous, such that even though their global degree of nonseparability
remains constant, locally it decreases to a minimum value as z tends to
infinit. We corroborated this quantitatively using the Hellinger distance, a
novel metric for vectorness that applies to spatially-disjoint vector modes. To
the best of our knowledge, HCVBs are the second family of vector beams in which
this behaviour has been observed, paving the way for applications in optical
tweezing or information encryption.
