An advanced atmospheric dispersion corrector: The Magellan visible AO camera

Derek Kopon, Laird M. Close, Victor Gasho

Research output: Chapter in Book/Report/Conference proceedingConference contribution

13 Scopus citations


In addition to the BLINC/MIRAC IR science instruments, the Magellan adaptive secondary AO system will have an EEV CCD47 that can be used both for visible AO science and as a wide-field acquisition camera. The effects of atmospheric dispersion on the elongation of the diffraction limited Magellan adaptive optics system point spread function (PSF) are significant in the near IR. This elongation becomes particularly egregious at visible wavelengths, culminating in a PSF that is 2000 μm long in one direction and diffraction limited (30-60 μm) in the other over the wavelength band 0.5-1.0 μm for a source at 45°zenith angle. The planned Magellan AO system consists of a deformable secondary mirror with 585 actuators. This number of actuators should be sufficient to nyquist sample the atmospheric turbulence and correct images to the diffraction limit at wavelengths as short as 0.7 μm, with useful science being possible as low as 0.5 μm. In order to achieve diffraction limited performance over this broad band, 2000 μm of lateral color must be corrected to better than 10 μm. The traditional atmospheric dispersion corrector (ADC) consists of two identical counter-rotating cemented doublet prisms that correct the primary chromatic aberration. We propose two new ADC designs: the first consisting of two identical counter-rotating prism triplets, and the second consisting of two pairs of cemented counter-rotating prism doublets that use both normal dispersion and anomalous dispersion glass in order to correct both primary and secondary chromatic aberration. The two designs perform 58% and 68%, respectively, better than the traditional two-doublet design. We also present our design for a custom removable wide-field lens that will allow our CCD47 to switch back and forth between an 8.6" FOV for AO science and a 25.8" FOV for acquisition.

Original languageEnglish (US)
Title of host publicationAdaptive Optics Systems
StatePublished - 2008
EventAdaptive Optics Systems - Marseille, France
Duration: Jun 23 2008Jun 26 2008

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X


OtherAdaptive Optics Systems

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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