Parasitic interference in classical and nulling stellar interferometry

摘要

A variety of instrumental effects can corrupt the observable quantities in optical or nulling stellar interferometry.One such effect is parasitic interference, which can occur inside an interferometric instrument. Because ofdiffraction effects related to beam propagation along finite size optics, or parasitic reflections inside transmittingoptics, a coherent crosstalk may occur between the beams and create a parasitic interference pattern superimposedon the genuine one. We developed an analytical approach to describe the impact of this effect on the observablesof classical and nulling stellar interferometers. Considering classical interferometry, we show that differentialphase and closure phase are both corrupted, depending on the crosstalk level and the residual piston betweenthe beams. Considering typical specifications of piston correction of ground-based interferometers (≈ 100 nm),the detection of hot Jupiter-like planets by differential phase implies a tolerance on the parasitic flux to about5% of the incident intensity. Also, we show that the closure phase relation does not remove this parasiticcontribution. The corresponding corrupted closure phase is not zero for an unresolved source, and depends onthe residual piston. Considering nulling interferometry, we show that parasitic effects modify the transmissionmap level, depending on the crosstalk level and the phase shift between primary and secondary beams. In theextreme case of a pi-phase shift, the crosstalk effect implies a decrease of the final output signal-to-noise ratio.Numerical simulations, adapted to handle consistently crosstalk, are then performed to estimate this degradationand validate our theoretical study.© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.