High-resolution image reconstruction: the case of the Large Binocular Telescope (LBT)

Abstract

In this paper we give a survey of the methods we have developed for multiple image deconvolution, with application to the reconstruction of the images of the Large Binocular Telescope (LBT). We first describe the main features of LBT and of the Fizeau interferometer, denoted LINC-NIRVANA, that will be one of the basic instruments of the telescope. It will allow to reach the resolution of a 22.8 m mirror by combining different images taken with different orientations of the baseline. Next we discuss the problem of multiple image deconvolution, that is crucial for obtaining a unique high-resolution image from the multiple images provided by LINC-NIRVANA. We present the state-of-the art of the methods based on the Richardson-Lucy (RL) approach and we discuss topics such as computational efficiency, correction of boundary effects and super-resolution. Then, in the perspective of going beyond RL, we extend to the problem of multiple image deconvolution the split gradient method (SGM) that is a general approach to the design of iterative methods for the constrained minimization of regularized functionals. Finally we present an application of SGM to the regularized reconstruction of objects with high-dynamic range. The different methods are illustrated with examples taken from the many numerical experiments we performed on this problem.