Partially coherent vortex beams with a separable phase Bogatyryova, Galina V. ; Fel'de, Christina V. ; Polyanskii, Peter V. ; Ponomarenko, Sergey A. ; Soskin, Marat S. ; Wolf, Emil Abstract Publication: Optics Letters Pub Date: June 2003 DOI: 10.1364/OL.28.000878 Bibcode: 2003OptL...28..878B