RT Journal Article T1 Signal representation on the angular Poincare sphere, based on second-order moments A1 Bastiaans, Martin J. A1 Alieva Krasheninnikova, Tatiana AB Based on the analysis of second-order moments, a generalized canonical representation of a two-dimensional optical signal is proposed, which is associated with the angular Poincare sphere. Vortex-free ( or zero-twist) optical beams arise on the equator of this sphere, while beams with a maximum vorticity ( or maximum twist) are located at the poles. An easy way is shown how the latitude on the sphere, which is a measure for the degree of vorticity, can be derived from the second-order moments. The latitude is invariant when the beam propagates through a first-order optical system between conjugate planes. To change the vorticity of a beam, a system that does not operate between conjugate planes is needed, with the gyrator as the prime representative of such a system. A direct way is derived to find an optical system ( consisting of a lens, a magnifier, a rotator, and a gyrator) that transforms a beam with an arbitrary moment matrix into its canonical form. PB Optical Society of America SN 1084-7529 YR 2010 FD 2010-04 LK https://hdl.handle.net/20.500.14352/44417 UL https://hdl.handle.net/20.500.14352/44417 LA eng NO © 2010 Optical Society of America. The financial support of the Spanish Ministry of Science and Innovation under project TEC2008-04105 and the Santander-Complutense project PR-34/07-15914 is acknowledged. NO Spanish Ministry of Science and Innovation NO Santander-Complutense DS Docta Complutense RD 16 abr 2025