Determination of an optical vortex topological charge using an astigmatic transform
V.V. Kotlyar
, A.A. Kovalev, A.P. Porfirev


Image Processing Systems Institute оf RAS, – Branch of the FSRC “Crystallography and Photonics” RAS, Samara, Russia,
Samara National Research University, Samara, Russia

Full text of article: Russian language.


It It is shown both theoretically and experimentally that if a cylindrical lens is placed into a laser beam, having an optical vortex with integer topological charge n and on-axis intensity null, then at the double focal distance behind the lens, the n-fold degenerate intensity null is split into n isolated intensity nulls. These intensity nulls lie on a straight line in the transverse plane at an angle of + 45 or – 45 degrees to the axis of the cylindrical lens, depending on the vortex helicity direction (i.e. sign of the topological charge). Experiments show that such a method can be used to determine higher-order topological charges up to n = 100.

optical vortex, topological charge, cylindrical lens, astigmatic transform.

Kotlyar VV, Kovalev AA, Porfirev AP. Determination of an optical vortex topological charge using an astigmatic transform. Computer Optics 2016; 40(6): 781-792. DOI: 10.18287/2412-6179-2016-40-6-781-792.


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