A Short Presentation of
Ongoing AO Workat Lund Observatory
Mette Owner-PetersenLund Observatory
Workshop for “Forskarskolen i Rymdteknik”Gothenburg 12/9 – 13/9 Gothenburg
Adaptive Optics
What is Adaptive Optics?
Answer:
Real-time Improvement of the Quality of Images whichare degraded due to dynamical perturbations of theimaging system
Peak Intensity (Strehl Ratio)
Resolution (FWHM)
Contrast (Background Level)
-10 -5 0 5 10
0.2
0.4
0.6
0.8
1
Strehl Ratio
FWHM
Background
-10 -5 0 5 10
0.2
0.4
0.6
0.8
1
Strehl Ratio
FWHM
Background
Strehl Ratio: Detection of faint objects
FWHM: Resolving bright objects in crowded fields
Contrast: Direct Exo-Planet observation
What is Meant by Image Quality?
Point Image (PSF)
Different AO Modes
Single Conjugate Adaptive Optics (SCAO). One DM and one guide star -> High Strehl but small corrected field.
Ground Layer Adaptive Optics (GLAO). The easy game. One DM and several guide stars -> Low Strehl but narrow FWHM over large field.
Multi Conjugate Adaptive Optics (MCAO). Several DMs and several guide stars -> High Strehl and large corrected field.
Extreme Adaptive Optics (ExAO). The hard bargain One DM and one Guide Star. Complicated filtering in both image and pupil plane -> Extremely high contrast.
How to Make it Work
Analytical performance evaluation
Confirmation by simulations
Lab verifications if needed
Optical modeling
“The real thing”
Simulations of AO perfomance for the Euro50. Integrated modeling PhD project for Anita Enmark
DCAO on the Lunda – Moon and for terrestrial applications Collaboration with Dept. of Applied Optics in Galway and FOI Sweden PhD project for Per Knutsson
DCAO for wide - field retinal imaging Collaboration with Dept. of Ophthalmology in Gothenburg
Previous: Analytical performance evaluations Experimental verification of expected DCAO performance
Ongoing AO Work
Correction for AtmosphereLa Palma 7-Layer Model
0 s < t < 0.1 s No AO correction0.1 s < t < 0.6 s Slow correction for Focus & Tip/tilt0.6 s < t < 1.1 s AO ON
Specification for AO: Strehl > 0.58
Euro50 PSF @ λ=2.2 μm Scale 00.3
S-H pattern SubimageS-H pattern Subimage
The Moon DCAO Experiment
Zemax ModelCelestron
DM10 km
DM210 km
Sci. Cam.
Tip /Tilt
WFS
Goal of the experiment: Emulation of K – band performance of SCAO, GLAO and DCAO on a 7.5 m telescope
5 guide stars in a cross
Specific Address:Field gain going from SCAO to DCAO
The Lund DCAO Demonstrator
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