title: Improving vector vortex waveplates for high-contrast coronagraphy.
abstract: Vector vortex waveplates (VVWs) open the door to new techniques in stellar coronagraphy and optical communications, but the performance of currently available liquid-crystal-polymer-based VVWs tends to be limited by defects in the axial region of the vortex pattern. As described here, several steps allow for a reduction in the size of such axial defects, including the use of photoalignment materials with high photosensitivity and reversible response, and a reduction in exposure energy. Moreover, redistributing the writing beam's intensity from the axial region to its periphery (using a VVW) allows the production of large area VVWs with a small defect area. Finally, using VVWs as linear to axial polarization converters allows producing VVWs of higher topological charge, while also reducing the photoalignment time to a few minutes. These steps have allowed the fabrication of VVWs with topological charges of 1 and 2 with central defect sizes below 3 μm.
authors.affiliation: BEAM Engineering for Advanced Measurements Co., 809 S. Orlando Ave., Suite I, Winter Park, FL 32789, USA.
authors.forename: Sarik R
authors.initials: SR
authors.lastname: Nersisyan
authors.forename: Nelson V
authors.initials: NV
authors.lastname: Tabiryan
authors.forename: Dimitri
authors.initials: D
authors.lastname: Mawet
authors.forename: Eugene
authors.initials: E
authors.lastname: Serabyn
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D007089:Image Enhancement / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*; D061351:Telescopes