Crosstalk in image plane beam combination for optical interferometers

Abstract

Image plane beam combination in optical interferometers multiplexes the interference fringes from multiple baselines onto a single detector. The beams of starlight are arranged in a non-redundant pattern at the entrance of the combiner so that the signal from each baseline can be separated from one another in the frequency domain. If the signals from different baselines overlap in the frequency domain, this can give rise to a systematic error in the fringe measurements known as baseline crosstalk. In this paper we quantify crosstalk arising from the combination of atmospheric seeing and beam propagation over distances of order hundreds of metres. We find that in idealised conditions atmospheric wavefront errors and beam propagation do not contribute to crosstalk. However, when aperture stops are included in the optical beam train we observe that wavefront errors can result in squared visibility errors arising from crosstalk as high as $\Delta V^2=6.6\times 10^{-3}$ under realistic observing conditions.

arXiv comment15 pages, 23 figures, accepted for publication in MNRAS

References in corpus (5)

• First Results from the CHARA Array. II. A Description of the Instrument
• Imaging the spotty surface of Betelgeuse in the H band
• Radiative hydrodynamics simulations of red supergiant stars: II. simulations of convection on Betelgeuse match interferometric observations
• Numerical Simulations of Pinhole and Single Mode Fibre Spatial Filters for Optical Interferometers
• The convective surface of the red supergiant Antares. VLTI/PIONIER interferometry in the near infrared