High dynamic range imaging with a single-mode pupil remapping system : a self-calibration algorithm for redundant interferometric arrays

摘要

The correction of the influence of phase corrugation in the pupil plane is afundamental issue in achieving high dynamic range imaging. In this paper, weinvestigate an instrumental setup which consists in applying interferometrictechniques on a single telescope, by filtering and dividing the pupil with anarray of single-mode fibers. We developed a new algorithm, which makes use ofthe fact that we have a redundant interferometric array, to completelydisentangle the astronomical object from the atmospheric perturbations (phaseand scintillation). This self-calibrating algorithm can also be applied to any- diluted or not - redundant interferometric setup. On an 8 meter telescopeobserving at a wavelength of 630 nm, our simulations show that a single modepupil remapping system could achieve, at a few resolution elements from thecentral star, a raw dynamic range up to 10^6; depending on the brightness ofthe source. The self calibration algorithm proved to be very efficient,allowing image reconstruction of faint sources (mag = 15) even though thesignal-to-noise ratio of individual spatial frequencies are of the order of0.1. We finally note that the instrument could be more sensitive by combiningthis setup with an adaptive optics system. The dynamic range would however belimited by the noise of the small, high frequency, displacements of thedeformable mirror.