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)

A Generic Example of Adaptive Optics

The Shack-Hartmann Wavefront Sensor

Other design principles are possible

How it looks in Reality

From the William Herschel telescope on La Palma

With and Without Adaptive Optics

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”

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

Wide Field Retinal Imaging

First light very soon!

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

The Lund DCAO Demonstrator