We describe the calibration method to be used for the off-axis laser guide stars at the Large Binocular Telescope’s (LBT’s) advanced Rayleigh guided ground layer adaptive optics system facility and the optical design of a dedicated calibration unit. Several possible solutions for generating artificial stars with the same wavefront as the real beacons were investigated. We find the use of a computer-generated hologram to be the best solution to the problem of producing aberrated light exactly matching that delivered by the primary mirror of the telescope. A detailed design and tolerance analysis is complete and the project is currently moving into the fabrication phase.
© 2010 Optical Society of America
Laser Guide Star System
Original Manuscript: April 20, 2010
Manuscript Accepted: May 21, 2010
Published: June 25, 2010
Christian Schwab and Andrew Rakich, "Rayleigh laser guide star calibration unit for the Large Binocular Telescope," Appl. Opt. 49, G53-G59 (2010)