Design and tests for the correction of atmospheric and instrumental effects on color-differential phase with AMBER/VLTI

摘要

The near-infrared instrument AMBER at the VLTI allows, among other interferometric observables, the simultaneous measurement of the phase between various spectral channels. Color-differential phase thus yields spatial and spectral information on unresolved sources, and could lead to such ambitious goals as the spectroscopy of nearby hot, giant exoplanets. This will require, though, an extreme stability on the measurement, which is likely to be affected by chromatic effects at the various stages of the light path. We present how AMBER has been designed to minimize and to calibrate such effects. We give estimates of their contributions from different origins, and present recent measurements of the instrumental stability. We discuss the possibility to supress the residual chromatic effects in post-data treatment in order to reach a precision limited by the photon noise on the differential phase.