CONFERENCE PROCEEDINGS
Advanced Search >
Home > Proceedings > Volume 7012 > Article
Translator Disclaimer
10 July 2008 The use of primary mirrors as Hartmann masks for in situ alignment of segmented mirror telescopes
Steven M. Crawford; Martyn Wells; Hitesh Gajjar
Author Affiliations +
Proceedings Volume 7012, Ground-based and Airborne Telescopes II; 70123P (2008) https://doi.org/10.1117/12.788840
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France
Abstract
Segmented primary mirrors dominate the current generation of 10m class telescopes as well as the designs for the next generation of Extremely Large Telescopes (ELT's). The complex nature of these telescopes is demonstrated by the long time periods associated with their commissioning and the difficulty of performing high precision optical alignments. However, additional tools to provide in situ measurements of their optical alignment can be provided by making use of the individual mirrors of a segmented primary; with the ability to move in six degrees of freedom, the individual mirrors can be deployed to trace multiple optical paths through the telescope. In this paper we describe how it is possible to use the segments themselves to create a number of Hartmann masks that allow focus and other aberrations to be measured using a standard imaging camera rather than a dedicated wavefront sensor. The Southern African Large Telescope (SALT), with a primary mirror composed of 91 1m segments, is used as an example. The segments were arranged to create eight Hartmann masks to measure the optical alignment. Through imaging data obtained at the telescope, the sensitivity of this method to changes in focus along with aberrations inherent in the system is demonstrated through Zernike polynomial fits to the observed patterns. Finally, we present simulations of possible patterns for use on future ELT's.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Citation Download Citation
Steven M. Crawford, Martyn Wells, and Hitesh Gajjar "The use of primary mirrors as Hartmann masks for in situ alignment of segmented mirror telescopes", Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 70123P (10 July 2008); doi: 10.1117/12.788840; https://doi.org/10.1117/12.788840
ACCESS THE FULL ARTICLE
PERSONAL SIGN IN
Full access may be available with your subscription
 
Forgot your username?
Forgot your password?
No SPIE account? Create an account
or Institutional Sign In via Shibboleth
PURCHASE THIS CONTENT
SUBSCRIBE TO DIGITAL LIBRARY
50 downloads per 1-year subscription
Members: $195
Non-members: $335 ADD TO CART
25 downloads per 1 - year subscription
Members: $145
Non-members: $250 ADD TO CART
PURCHASE SINGLE ARTICLE
Includes PDF, HTML & Video, when available
Members: $14.40
Non-members: $18.00 ADD TO CART
PROCEEDINGS
 9 PAGES
DOWNLOAD PDF SAVE TO MY LIBRARY
SHARE
GET CITATION
< Previous Article
|
Next Article >
Advertisement
Advertisement
KEYWORDS
RELATED CONTENT
Subscribe to Digital Library
Receive Erratum Email Alert
Back to Top