POAMI: a Photon Orbital Momentum Interferometer for residual starlight cancellation in vectorial vortex coronagraphy

Riaud, Pierre

doi:10.1093/mnras/stu1761

Cited by 1 publication

(1 citation statement)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, the contrast ratio between the off axis sources and the residual central starlight is improved increasing the detection probability for off axis sources. This setup is a simplified version of the one proposed by P. Riaud 13 where four Dove prisms are implied to correct the differential rotation and overcome possible wavefront aberrations. In this paper, we focus on the effect of the Dove on the polarization and their impact on the interferometer performance.…”

Section: Introductionmentioning

confidence: 99%

A Mach-Zehnder interferometer based on orbital angular momentum for improved vortex coronagraph efficiency

Piron

Delacroix²,

Huby

et al. 2015

SPIE Proceedings

View full text Add to dashboard Cite

The Annular Groove Phase Mask (AGPM) is a vectorial vortex phase mask. It acts as a half-wave plate with a radial fast axis orientation operating in the mid infrared domain. When placed at the the focus of a telescope element provides a continuous helical phase ramp for an on axis sources, which creates the orbital angular momentum. Thanks to that phase, the intensity of the central source is canceled by a down-stream pupil stop, while the off axis sources are not affected. However due to experimental conditions the nulling is hardly perfect. To improve the null, a Mach-Zehnder interferometer containing Dove prisms differently oriented can be proposed to sort out light based on its orbital angular momentum (OAM). Thanks to the differential rotation of the beam, a π phase shift is achieved for the on axis light affected by a non zero OAM. Therefore the contrast between the star and its faint companion is enhanced. Nevertheless, due the Dove prisms birefringence, the performance of the interferometer is relatively poor. To solve this problem, we propose to add a birefringent wave-plate in each arm to compensate this birefringence. In this paper, we will develop the mathematical model of the wave front using the Jones formalism. The performance of the interferometer is at first computed for the simple version without the birefringent plate. Then the effect of the birefringent plate is be mathematically described and the performance is re-computed.

show abstract

Section: Introductionmentioning

confidence: 99%