21 July 2010 The Atmospheric piston simulator as an integral part of the calibration unit of LINC - NIRVANA
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The atmospheric piston simulator is an integral part of the calibration unit of LINC-NIRVANA, the Fizeau interferometric imager for the Large Binocular Telescope. The calibration unit will be necessary to align and set up the different opto - mechanical subsystems of the instrument. It will assist in (1) the alignment of the optics via reference fibers; (2) establishing zero optical path difference using a balanced fiber splitter; (3) flat fielding of the detectors with an integrating sphere; (4) correction of the non-common path aberrations using a fiber-based phase diversity source; and (5) calibration of the adaptive optics with a rotating reference fiber plate. Substantial testing and verification of the fringe tracker under as realistic as possible conditions in the lab is desirable, since the performance of the fringe tracker will ultimately determine the high angular resolution imaging capability of LINC-NIRVANA as a whole. We are therefore also constructing an atmospheric piston simulator working in the J and H photometric bands. As with many of the other calibration unit sub-systems, our design concept is mainly fiber based. Opto - electronic phase modulators will be used to introduce the piston sequences. The control system of the piston modulators will allow for easy implementation of different vibration power spectra. This will enable us to test and demonstrate the capabilities of the fringe tracker under realistic conditions.
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R. Follert, T. M. Herbst, P. Bizenberger, F. DeBonis, "The Atmospheric piston simulator as an integral part of the calibration unit of LINC - NIRVANA", Proc. SPIE 7734, Optical and Infrared Interferometry II, 77343Z (21 July 2010); doi: 10.1117/12.857063; https://doi.org/10.1117/12.857063

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