| Issue |
2010
|
|
|---|---|---|
| Article Number | 04007 | |
| Number of page(s) | 5 | |
| Section | Laser guide stars | |
| DOI | https://doi.org/10.1051/ao4elt/201004007 | |
| Published online | 24 February 2010 | |
Design of an holographic off-axis calibration light source for ARGOS at the LBT
1
ZAH-Landessternwarte, Universitat Heidelberg,
Germany
2
Max-Planck Institut fur Astronomie, Heidelberg
3
DIOPTIC GmbH, Bensheim
Germany
a e-mail: cschwab@lsw.uni-heidelberg.de
We report on the design of an artificial light source for ARGOS, the multiple Rayleigh laser guide star (LGS) facility at the Large Binocular Telescope (LBT). Our light source mimics the expected night-time illumination of the adaptive secondary mirror (ASM) by the laser beacons very accurately and provides a way to check the achieved performance, allowing thorough testing of the system during day time. The optical design makes use of computer generated holograms (CGH) and strong aspheres to achieve a very small residual wavefront error. Additional structures on the CGH facilitate quick and precise alignment of the optics in the prime focus. We demonstrate that the scheme can be applied to the current European Extremely Large Telescope (E-ELT) design in a similar way.
© Owned by the authors, published by EDP Sciences, 2010