Polarization effects in aperture synthesis arrays

Publisher Website
Google Scholar
Abstract
We describe the visibility function in polarized light for a cophased N-aperture synthesis array made of ground-based optical telescopes. Instrumental polarization induces attenuations depending on both the differential field rotations and the phase delays from incoming beams, whereas the combination of N beams leads to a power transmission divided by N in the modulation transfer function. For asymmetrical arrays, we optimize two compensators for field rotation: three-reflection optics in rotation around the optical axis of each interferometric arm and a pyramidal beam-combiner similar to a very large Cassegrain telescope. These correctors are equivalent in terms of visibility losses so that trade-offs must be found between mechanical requirements and SNR. Finally, the separation of the two polarizations before recording the fringes is very attractive for future interferometric projects since it greatly reduces the data bias and also provides visibilities in polarized light and therefore new constraints on polarization mechanisms in stellar atmospheres. © 1997 Society of Photo-Optical Instrumentation Engineers.

This publication has 0 references indexed in Scilit: