Aperture synthesis imaging with the LBT: reconstruction of diffraction-limited images from LBT LINC-NIRVANA data using the Richardson-Lucy and regularized building block method

Abstract

The regularized and space-variant Building Block method allow the reconstruction of diffraction-limited aperture-synthesis images from Large Binocular Telescope (LBT) LINC-NIRVANA data. Images with the diffraction-limited resolution of a 22.8 m single-dish telescope can be reconstructed if raw images are taken at several different hour angles. Computer-generated and laboratory LBT interferograms were simulated that are similar to the data which can be obtained with the LINC-NIRVANA beam combiner instrument. From the simulated interferograms, diffraction-limited images were reconstructed with the regularized Building Block method, which is an extension of the Building Block method. We compare the Building Block reconstructions to images obtained with the Richardson-Lucy (RL) method and the Ordered Subsets Expectation Maximization (OSEM) method. Our image reconstruction studies were performed with computer-simulated J-band and laboratory H-band raw data of a galaxy with simulated total magnitudes of J = 16 to 18 and H = 16 to 19, respectively. One of the faintest structures in the images has a brightness of J~25. The simulated reference stars within the isoplanatic patch have magnitudes of J = 20 - 21 and H = 19. All three methods are able to reconstruct diffraction-limited images of similar quality.