Vortex-phase filtering technique for extracting spatial information from unresolved sources

Abstract

A white light vortex coronagraph was used to experimentally achieve sub-resolution detection. The angular location of the centroid, $γ$, and the angular extent of circular pinhole sources, $Θ$, were measured to within errors of $δγ= \pm0.015\,λ/D$ and $δΘ= \pm0.026\,λ/D$. This technique has two advantages over conventional imaging: simple power measurements are made and shorter exposure times may be required to achieve a sufficient signal-to-noise ratio.