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Adaptive Optics. A Short Presentation of Ongoing AO Work at Lund Observatory Mette Owner-Petersen Lund Observatory. Workshop for “Forskarskolen i Rymdteknik” Gothenburg 12/9 – 13/9 Gothenburg. What is Adaptive Optics?. Answer: Real-time Improvement of the Quality of Images which

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Adaptive Optics

A Short Presentation

of

Ongoing AO Work

at Lund Observatory

Mette Owner-Petersen

Lund Observatory

Workshop for “Forskarskolen i Rymdteknik”

Gothenburg 12/9 – 13/9 Gothenburg


What is Adaptive Optics?

Answer:

Real-time Improvement of the Qualityof Images which

are degraded due to dynamical perturbations of the

imaging system


What is Meant by Image Quality?

  • Peak Intensity (Strehl Ratio)

  • Resolution (FWHM)

  • Contrast (Background Level)

Point Image

(PSF)

Strehl Ratio:Detection of faint objects

FWHM:Resolving bright objects in crowded fields

Contrast:Direct Exo-Planet observation



The Shack-Hartmann Wavefront Sensor

Other design principles are possible


How it looks in Reality

From the William Herschel telescope on La Palma



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.


SCAO versus MCAO

Uncorrected SCAO MCAO


How to Make it Work

  • Analytical performance evaluation

  • Confirmation by simulations

  • Lab verifications if needed

  • Optical modeling

  • “The real thing”


Ongoing AO Work

  • 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


Correction for atmosphere la palma 7 layer model
Correction for AtmosphereLa Palma 7-Layer Model

Euro50 PSF @ λ=2.2 μm Scale 00.3

0 s < t < 0.1 s No AO correction

0.1 s < t < 0.6 s Slow correction for Focus & Tip/tilt

0.6 s < t < 1.1 s AO ON

Specification for AO: Strehl > 0.58


The Moon DCAO Experiment

WFS

Sci. Cam.

DM1

0 km

DM2

10 km

Tip /Tilt

Zemax Model

Celestron


Wide Field Retinal Imaging

First light very soon!


The Lund DCAO Demonstrator

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



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