Methods of Multi-Conjugate Adaptive Optics for Astronomy

Forskningsoutput: AvhandlingDoktorsavhandling (sammanläggning)

Standard

Methods of Multi-Conjugate Adaptive Optics for Astronomy. / Flicker, Ralf.

Lund Observatory, Lund University, 2003. 130 s.

Forskningsoutput: AvhandlingDoktorsavhandling (sammanläggning)

Harvard

Flicker, R 2003, 'Methods of Multi-Conjugate Adaptive Optics for Astronomy', Doktor, Astronomi.

APA

Flicker, R. (2003). Methods of Multi-Conjugate Adaptive Optics for Astronomy. Lund Observatory, Lund University.

CBE

Flicker R. 2003. Methods of Multi-Conjugate Adaptive Optics for Astronomy. Lund Observatory, Lund University. 130 s.

MLA

Flicker, Ralf Methods of Multi-Conjugate Adaptive Optics for Astronomy Lund Observatory, Lund University. 2003.

Vancouver

Flicker R. Methods of Multi-Conjugate Adaptive Optics for Astronomy. Lund Observatory, Lund University, 2003. 130 s.

Author

Flicker, Ralf. / Methods of Multi-Conjugate Adaptive Optics for Astronomy. Lund Observatory, Lund University, 2003. 130 s.

RIS

TY - THES

T1 - Methods of Multi-Conjugate Adaptive Optics for Astronomy

AU - Flicker, Ralf

N1 - Defence details Date: 2002-05-08 Time: 14:30 Place: Lundmarksalen, Lund Observatory, Sölvegatan 27 External reviewer(s) Name: Dainty, Chris Title: Prof Affiliation: Galway, Ireland ---

PY - 2003

Y1 - 2003

N2 - This work analyses several aspects of multi-conjugate adaptive optics (MCAO) for astronomy. The research ranges from fundamental and technical studies for present-day MCAO projects, to feasibility studies of high-order MCAO instruments for the extremely large telescopes (ELTs) of the future. The first part is an introductory exposition on atmospheric turbulence, adaptive optics (AO) and MCAO, establishing the framework within which the research was carried out. The second part (papers I-VI) commences with a fundamental design parameter study of MCAO systems, based upon a first-order performance estimation Monte Carlo simulation. It is investigated how the number and geometry of deformable mirrors and reference beacons, and the choice of wavefront reconstruction algorithm, affect system performance. Multi-conjugation introduces the possibility of optically canceling scintillation in part, at the expense of additional optics, by applying the phase correction in a certain sequence. The effects of scintillation when this sequence is not observed are investigated. As a link in characterizing anisoplanatism in conventional AO systems, images made with the AO instrument Hokupa'a on the Gemini-North Telescope were analysed with respect to the anisoplanatism signal. By model-fitting of simulated data, conclusions could be drawn about the vertical distribution of turbulence above the observatory site (Mauna Kea), and the significance to future AO and MCAO instruments with conjugated deformable mirrors is addressed. The problem of tilt anisoplanatism with MCAO systems relying on artificial reference beacons - laser guide stars (LGSs) - is analysed, and analytical models for predicting the effects of tilt anisoplanatism are devised. A method is presented for real-time retrieval of the tilt anisoplanatism point spread function (PSF), using control loop data. An independent PSF estimation of high accuracy is thus obtained which enables accurate PSF photometry and deconvolution. Lastly, a first-order performance estimation method is presented by which MCAO systems for ELTs may be studied efficiently, using sparse matrix techniques for wavefront reconstruction and a hybrid numerical/analytical simulation model. MCAO simulation results are presented for a wide range of telescope diameters up to 100 meters, and the effects of LGSs and a finite turbulence outer scale are investigated.

AB - This work analyses several aspects of multi-conjugate adaptive optics (MCAO) for astronomy. The research ranges from fundamental and technical studies for present-day MCAO projects, to feasibility studies of high-order MCAO instruments for the extremely large telescopes (ELTs) of the future. The first part is an introductory exposition on atmospheric turbulence, adaptive optics (AO) and MCAO, establishing the framework within which the research was carried out. The second part (papers I-VI) commences with a fundamental design parameter study of MCAO systems, based upon a first-order performance estimation Monte Carlo simulation. It is investigated how the number and geometry of deformable mirrors and reference beacons, and the choice of wavefront reconstruction algorithm, affect system performance. Multi-conjugation introduces the possibility of optically canceling scintillation in part, at the expense of additional optics, by applying the phase correction in a certain sequence. The effects of scintillation when this sequence is not observed are investigated. As a link in characterizing anisoplanatism in conventional AO systems, images made with the AO instrument Hokupa'a on the Gemini-North Telescope were analysed with respect to the anisoplanatism signal. By model-fitting of simulated data, conclusions could be drawn about the vertical distribution of turbulence above the observatory site (Mauna Kea), and the significance to future AO and MCAO instruments with conjugated deformable mirrors is addressed. The problem of tilt anisoplanatism with MCAO systems relying on artificial reference beacons - laser guide stars (LGSs) - is analysed, and analytical models for predicting the effects of tilt anisoplanatism are devised. A method is presented for real-time retrieval of the tilt anisoplanatism point spread function (PSF), using control loop data. An independent PSF estimation of high accuracy is thus obtained which enables accurate PSF photometry and deconvolution. Lastly, a first-order performance estimation method is presented by which MCAO systems for ELTs may be studied efficiently, using sparse matrix techniques for wavefront reconstruction and a hybrid numerical/analytical simulation model. MCAO simulation results are presented for a wide range of telescope diameters up to 100 meters, and the effects of LGSs and a finite turbulence outer scale are investigated.

KW - Adaptive optics

KW - anisoplanatism

KW - laser guide stars

KW - performance estimation

KW - wavefront reconstruction

KW - extremely large telescopes

KW - optics

KW - Electromagnetism

KW - Elektromagnetism

KW - acoustics

KW - Astronomy

KW - akustik

KW - space research

KW - optik

KW - multi-conjugate

KW - cosmic chemistry

KW - Astronomi

KW - rymdvetenskap

KW - kosmisk kemi

KW - Fysicumarkivet A:2003:Flicker

M3 - Doctoral Thesis (compilation)

SN - 91-628-5625-1

PB - Lund Observatory, Lund University

ER -