17 July 2008 Use of field aberrations in the alignment of the Large Binocular Telescope optics
Author Affiliations +
It is now well-known that measurement of field-aberration, and in particular the asymmetric field-astigmatism, is required to break the degeneracy of tip-induced and de-centre-induced aberration that exists when only on-axis misalignment aberrations are considered. This paper discusses the application of the measurement of field-aberrations to the alignment of LBT optics. This application ranges from the use of wide field out-of-focus images to determine corrector tip for the red and blue prime-focus correctors, to the use of data acquired by off-axis Shack-Hartman wavefront sensors to actively reposition the hexapod-mounted primary and secondary mirrors so as to simultaneously remove both de-centre and tip/tilt such that the only remaining field-astigmatism has rotational symmetry about the centre of the detector. Also introduced is a novel method to calculate the misalignment aberrations based on an extension of the plate-diagram analysis. It is shown that this method is readily applicable to the calculation of misalignment aberrations for systems of three-or-more powered mirrors, with almost no more computational difficulty than that of the two-mirror case. Results are discussed, as well as work in progress in this area.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
A. Rakich, A. Rakich, J. M. Hill, J. M. Hill, C. J. Biddick, C. J. Biddick, D. L Miller, D. L Miller, T. Leibold, T. Leibold, "Use of field aberrations in the alignment of the Large Binocular Telescope optics", Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 70121L (17 July 2008); doi: 10.1117/12.789902; https://doi.org/10.1117/12.789902

Back to Top