Laboratoire d'Astrophysique Observatoire de Grenoble
BP 53
SF2A-
38041 GRENOBLE Cédex 9
Grenoble, FRANCE
Presentation 1 : Oral
SNR on visibilities for fibered interferometers
Tatulli E., Mege P., Chelli A., Malbet F.
Spatial filtering properties of optical waveguides (monomode
fibers, integrated optics) are more and more used in ground-based
interferometry for we know it provides highly accurate visibilities measurements. We compute the theoretical SNR on the modal visibility with partial adaptative corrections, taking into account photon noise,additive noise and the coupling variations at the wavefront/fiber interface.
We show that, except for point sources, atmospheric fluctuations add a pure turbulent term in the visibility error. This turbulent term is independent on the source brightness and is all the higher than the source is extended. We conclude that i) for strong fluxes, the SNR per interferogram saturates to a constant value and, ii) large
Strehl fluctuations will significantly decrease the limiting magnitude. This plead in favor of high-order adaptive optics combined with the waveguide.