We describe a two-dimensional method to extract the phase of turbulence-blurred near infrared interferograms in the plane of the telescope pupil. The instrument and its principle have been described in a previous paper (Mariotti et al. 1992).
The phase data are obtained from near-infrared interference fringes produced by a Michelson interferometer in the image of the telescope pupil. We have developed an equivalent of the Knox-Thompson algorithm, using the spatial correlation of the phase over the pupil to recover the actual 2-D phase of the complex visibility function. We compute and average the spatial gradients of the instantaneous phase and a minimal norm least squares method is then used to recover the actual phase over the pupil. The modulus and the phase can be used to recover diffraction-limited images.
We present an application of the method on a simulated binary system, together with first results on some astronomical data recently obtained at the 4.20m William Herschel Telescope of the Royal Greenwich Observatory at La Palma. Tentative deconvolutions are presented. The physical interpretation of these data will be presented in a forthcoming paper.
Keywords:
Infrared - Near Infrared - Interferometry - IR Arrays -
Circumstellar environment - Image reconstruction