Tilt anisoplanatism and PSF retrieval in LGS MCAO using a predictive controller
(2002) Beyond conventional adaptive optics : a conference devoted to the adaptive optics for extremely large telescopes. Proceedings of the Topical Meeting 58. p.377-377- Abstract
- It is shown how tilt anisoplanatism in laser-supported multi-conjugatedadaptive optics (MCAO) systems can be a) predicted from a prioriknowledge, b) compensated using additional natural guide stars (NGS),and c) estimated in real time from control loop data to allow PSFretrieval. As a consequence of the problems associated with retrievingatmospheric tip and tilt from laser guide star (LGS) measurements, anMCAO system without additional reference beacons will have a set of nullmodes that can not be measured by the LGS. These are the global tip andtilt modes, and three plate scale modes deriving principally fromtomographical combinations of quadratic modes (focus and astigmatisms).These modes can be compensated by introducing a NGS-supported... (More)
- It is shown how tilt anisoplanatism in laser-supported multi-conjugatedadaptive optics (MCAO) systems can be a) predicted from a prioriknowledge, b) compensated using additional natural guide stars (NGS),and c) estimated in real time from control loop data to allow PSFretrieval. As a consequence of the problems associated with retrievingatmospheric tip and tilt from laser guide star (LGS) measurements, anMCAO system without additional reference beacons will have a set of nullmodes that can not be measured by the LGS. These are the global tip andtilt modes, and three plate scale modes deriving principally fromtomographical combinations of quadratic modes (focus and astigmatisms).These modes can be compensated by introducing a NGS-supported null modecontrol loop totally decoupled from the LGS system. Invoking a prioriassumptions about the atmospheric turbulence, we compute the loss ofStrehl ratio from residual tilt anisoplanatism due to noise and servolag for some sample NGS configurations and magnitudes. PSF retrieval isdemonstrated in all cases. Results are obtained and compared using botha simple and a noise-weighted least squares estimator, and both anintegrating and a predictive linear controller. Finally, a method forreal time estimation is presented, and verification by monte carlogenerated loop data is work in progress. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/528019
- author
- Flicker, Ralf LU and Rigaut, François
- organization
- publishing date
- 2002
- type
- Chapter in Book/Report/Conference proceeding
- publication status
- published
- subject
- host publication
- Beyond conventional adaptive optics : ESO Conference and Workshop Proceedings
- editor
- Vernet, E ; Ragazzoni, S ; Esposito, S and Hubin, N
- volume
- 58
- pages
- 377 - 377
- publisher
- European Southern Observatory
- conference name
- Beyond conventional adaptive optics : a conference devoted to the adaptive optics for extremely large telescopes. Proceedings of the Topical Meeting
- conference location
- Venice, Italy
- conference dates
- 2001-05-07 - 2001-05-10
- ISBN
- 3923524617
- language
- English
- LU publication?
- yes
- id
- 180f25e8-0878-4535-abd2-678d16043cf3 (old id 528019)
- date added to LUP
- 2016-04-04 11:55:29
- date last changed
- 2018-11-21 21:08:01
@inproceedings{180f25e8-0878-4535-abd2-678d16043cf3, abstract = {{It is shown how tilt anisoplanatism in laser-supported multi-conjugatedadaptive optics (MCAO) systems can be a) predicted from a prioriknowledge, b) compensated using additional natural guide stars (NGS),and c) estimated in real time from control loop data to allow PSFretrieval. As a consequence of the problems associated with retrievingatmospheric tip and tilt from laser guide star (LGS) measurements, anMCAO system without additional reference beacons will have a set of nullmodes that can not be measured by the LGS. These are the global tip andtilt modes, and three plate scale modes deriving principally fromtomographical combinations of quadratic modes (focus and astigmatisms).These modes can be compensated by introducing a NGS-supported null modecontrol loop totally decoupled from the LGS system. Invoking a prioriassumptions about the atmospheric turbulence, we compute the loss ofStrehl ratio from residual tilt anisoplanatism due to noise and servolag for some sample NGS configurations and magnitudes. PSF retrieval isdemonstrated in all cases. Results are obtained and compared using botha simple and a noise-weighted least squares estimator, and both anintegrating and a predictive linear controller. Finally, a method forreal time estimation is presented, and verification by monte carlogenerated loop data is work in progress.}}, author = {{Flicker, Ralf and Rigaut, François}}, booktitle = {{Beyond conventional adaptive optics : ESO Conference and Workshop Proceedings}}, editor = {{Vernet, E and Ragazzoni, S and Esposito, S and Hubin, N}}, isbn = {{3923524617}}, language = {{eng}}, pages = {{377--377}}, publisher = {{European Southern Observatory}}, title = {{Tilt anisoplanatism and PSF retrieval in LGS MCAO using a predictive controller}}, volume = {{58}}, year = {{2002}}, }