The Large Binocular Telescope (LBT) on Mt. Graham in Southeastern Arizona uses two 8.4-meter diameter primary mirrors mounted side-by-side to produce a collecting area equivalent to an 11.8-meter circular aperture. We describe our use of active optics with the honeycomb primary mirrors to provide focussing, collimation and low-order active wavefront correction for the two prime focus cameras now operating on the telescope. We use a custom IDL program, LBCFPIA, to geometrically analyze extrafocal pupils in order to determine focus and wavefront corrections through third-order spherical aberration. We also describe that section of the telescope control system which manages primary mirror collimation and accepts wavefront correction requests from the instrument. We present active optics results obtained during commissioning of the prime focus cameras and during science observations.

Date Published: 10 July 2008
PDF: 10 pages
Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 70121M (10 July 2008); doi: 10.1117/12.789993

Published in SPIE Proceedings Vol. 7012:
Ground-based and Airborne Telescopes II
Larry M. Stepp; Roberto Gilmozzi, Editor(s)