Publications of the MPIfR
Optical & Infrared
Interferometry Group
Hofmann, K.-H., Driebe, T., Heininger,
M., Schertl, D., and Weigelt, G.
Reconstruction of aperture-synthesis images
from LBT LINC-NIRVANA data using the Richardson-Lucy and space-variant
Building Block method
A&A, 444, pg.983-993 (Section 'Instruments,
observational techniques, and data processing') (2005)
Abstract
We present a new method, the regularized and space-variant
Building Block method, which is able to
reconstruct 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 derived if raw images are taken at several
different hour angles.
We simulated computer-generated and
laboratory LBT interferograms that are similar to the data
which can be obtained with the LINC-NIRVANA beam combiner
instrument. From the simulated data, diffraction-limited
images were reconstructed with the regularized Building Block
method, which is an extension of the Building Block method
(Hofmann & Weigelt 1993, A&A, 278, 328). We
compare the Building Block reconstructions to images obtained
with the Richardson-Lucy (RL) method (Richardson 1972, J. Opt. Soc.
Am., 62, 55; Lucy 1974, AJ, 79, 745) and the Ordered Subsets
Expectation Maximization (OSEM)
method (Hudson & Larkin 1994, IEEE Trans. Med. Imag., 13, 601;
Bertero & Boccacci 2000, A&AS, 144, 181). 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 
to 18
and 
to 19,
respectively. One of the faintest structures in the images
has a brightness of 
.
The simulated reference stars
within the isoplanatic patch have magnitudes of
and
. All three methods
are able to
reconstruct diffraction-limited images with almost the same
quality. Furthermore, raw data with
space-variant point spread functions were simulated, and
diffraction-limited images were reconstructed using the
space-variant version of the Building Block method.
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