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A Scanning Hartmann Focus Test for the EUVI Telescopes aboard STEREOThe Solar TErrestrial RElations Observatory (STEREO), the third mission in NASA s Solar Terrestrial Probes program, was launched in 2006 on a two year mission to study solar phenomena like coronal mass ejections. STEREO consists of two nearly identical satellites, each carrying a suite of instruments that provide, among other data, simultaneous images of the Sun. One of these telescopes is the Extreme Ultraviolet Instrument (EUVI). There are two EUVI telescopes, one on each STEREO satellite (EUVI-A and EUVI-B). EUVI is a normal incidence, 98mm diameter, Ritchey-Chretien telescope designed to obtain wide field of view (approx.1deg) images of the Sun at short wavelengths (approx.20nm) using a CCD detector. The telescope entrance aperture is divided into four quadrants by a mask near the secondary mirror spider veins. A mechanism that rotates another mask allows only one of these sub-apertures to accept light from the Sun during an observation. The EUVI is thus four co-aligned, off-axis telescopes. Each off-axis segment on the primary and secondary mirrors has a different extreme ultraviolet coating stack. Furthermore, the aperture select mechanism is synchronized with a filter wheel mechanism near the CCD detector. The EUVI contains no focus mechanism. Models predict that the difference in on-orbit operating temperature and ambient clean room conditions yield a "best focus" difference between integration and operation of approx. 0.2mm.
Document ID
20070032104
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Ohl, R.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Antonille, S.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Aronstein, D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Dean, B.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Delmont, M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Eichord, W.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Frey, B.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Kubalak, D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Wilson, M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Redman, K.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hynes, S.
(Swales Aerospace Greenbelt, MD, United States)
Shiri, R.
(Johns Hopkins Univ. United States)
Smith, J. S.
(Johns Hopkins Univ. United States)
Thompson, P.
(Johns Hopkins Univ. United States)
Date Acquired
August 23, 2013
Publication Date
August 26, 2007
Subject Category
Astronomy
Meeting Information
Meeting: SPIE Optics and Photonics
Location: San Diego, CA
Country: United States
Start Date: August 26, 2007
End Date: August 30, 2007
Sponsors: International Society for Optical Engineering
Distribution Limits
Public
Copyright
Other

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