Vortex beams and quadrant detection for detecting barycenter motion of stars with polar orbiting exoplanets

Abstract

Exoplanets passing through the poles of their stars as seen from Earth may pose difficulties to conventional exoplanet detection techniques such as transit or radial velocity methods. This arises from the lack of appreciable transit and longitudinal Doppler shift. Here, we propose measuring the wobble of such stars by passing the starlight through a phase plate with a singularity, resulting to an asymmetric Gaussian beam with a vortex in the middle. A quadrant detector then measures the periodic increase and decrease in intensity on the left and right halves of the images, characteristic of the star moving around a barycenter.