Singular value representation of the coherence Poincaré sphere Jyrki Laatikainen, Ari T. Friberg, Olga Korotkova and Tero Setälä J. Eur. Opt. Society-Rapid Publ., 18 2 (2022) 12 Published online: 06 December 2022 DOI: 10.1051/jeos/2022012