Developing and testing an optical alignment system for SALT’s segmented primary mirror

Allan Wirth; Tom Gonsiorowski; Jennifer Roberts; Theresa L. Bruno; Jian Swiegers; Hitesh Gajjar; Arek Swat

doi:10.1117/12.551425

28 September 2004 Developing and testing an optical alignment system for SALT's segmented primary mirror

Allan Wirth, Tom Gonsiorowski, Jennifer Roberts, Theresa L. Bruno, Jian Swiegers, Hitesh Gajjar, Arek Swat

Proceedings Volume 5489, Ground-based Telescopes; (2004) https://doi.org/10.1117/12.551425
Event: SPIE Astronomical Telescopes + Instrumentation, 2004, Glasgow, United Kingdom

Abstract

The design of the Southern African Large Telescope (SALT), which is based closely on the Hobby-Eberly Telescope (HET) at the University of Texas but includes advances incorporating lessons learned from HET, is briefly reviewed. The flowdown of requirements from the optical error budget to the primary mirror control subsystems is presented. The techniques and algorithms used by the Center of Curvature Alignment Sensor (CCAS) to measure segment tilt and piston and estimate the global radius of curvature of the primary are discussed in detail. The steps in the process that allows CCAS to capture and identify segments misaligned by more than 70 arcsec and bring them into alignment with residual errors less than 50milli-arcsec is fully described. Next, the hardware and software designs of CCAS are presented, as well as the results of laboratory performance testing. CCAS has been installed and integrated with the primary mirror control system. Performance results of the integrated system over a range of environmental conditions will be shown. Finally, the overall results of this project are summarized and suggestions for future improvements presented.

Citation Download Citation

Allan Wirth, Tom Gonsiorowski, Jennifer Roberts, Theresa L. Bruno, Jian Swiegers, Hitesh Gajjar, and Arek Swat "Developing and testing an optical alignment system for SALT's segmented primary mirror", Proc. SPIE 5489, Ground-based Telescopes, (28 September 2004); https://doi.org/10.1117/12.551425

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