Fabrication and testing of l = 2 optical vortex phase masks for coronography.
In this paper we present the fabrication process and tests of two different types of l = 2 spiral phase plates (SPPs), designed for an Optical Vortex Coronagraph (OVC) in the visible wavelength regime. Each phase mask is realized dividing the spirals area in sectors respectively of 8 and 512 of levels using lithographic nanofabrication approach. The SPPs produces different optical vortices (OVs) with topological charge l that depends on the number of steps and on the wavelength. We found that the residual light in the central dark region of the OV tends to zero as the number of steps increases.
Mari
Elettra
E
CISAS G Colombo, University of Padua, Via Venezia 15 35131, Padova, Italy. elettra.mari@unipd.it
Anzolin
Gabriele
G
Tamburini
Fabrizio
F
Prasciolu
Mauro
M
Umbriaco
Gabriele
G
Bianchini
Antonio
A
Barbieri
Cesare
C
Romanato
Filippo
F