The Adaptive Optics Lucky Imager

High-resolution imaging in the visible on large ground-based telescopes

Jonathan CrassInstitute of Astronomy, University of Cambridge

SPIE Astronomical Telescopes and Instrumentation June 2014, Montreal

Craig Mackay, Rafael Rebolo-López, David King, Victor González Escalera, Marta Puga Antolín, Antonio Pérez Garrido, Lucas Labadie, Roberto López, Alex Oscoz, Jorge Andrés Pérez Prieto, Luis Rodríguez-Ramos, Sergio Velasco, Isidro Villo

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

• Motivation and background

• The Adaptive Optics Lucky Imager

• AO and lucky imaging systems

• Optical design & systems

• On-sky results

• Future work

Outline

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

How to get diffraction limited imaging in the optical?

Adaptive optics

It’s hard to do AO at optical wavelengths

Lucky imaging

Only works on telescopes up ~2.5m in diameter

Combine the two together – diffraction limited imaging in the visible

Motivation

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

Adaptive Optics and Lucky Imaging

HST - ACS Lucky – 10% Fourier – 20% Fourier – 50%

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

• The sharpest images come from the smallest fraction of images.

• Often the poorer quality images are only smeared in one direction.

• Garrel et al (PASP, 2012) suggested making the lucky selection in Fourier space rather than image space.

High-Efficiency Lucky Imaging

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

High-Efficiency Lucky Imaging

High-efficiency lucky imagingMackay 2013, MNRAS, 432, 702

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

• Initially for the 4.2m William Herschel Telescope

• Lucky Imaging based science instrument:• 4 × 1024 square EMCCDs (E2V CCD201) providing

2000×2000px imaging region• Pixel scale of 18-55 milliarcseconds in I-band• Field of view ranging from 37.5 to 112.5 arcseconds

• AO component:• ALPAO 241 actuator deformable mirror (DM241-25)• Non-linear curvature wavefront sensor• Comprises 2 EMCCDs

About AOLI

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

Non-linear Curvature Wavefront Sensor

• nlCWFS offers:• High sensitivity to low and high orders• Reconstruction with ≈100-1000 fewer photons than

conventional techniques Talk 9148-81 – Friday 11:05am (Jonathan Crass)

The AOLI low-order non-linear curvature wavefront sensor: laboratory and on-sky

results

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

AOLI Optics

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

Wavefront sensor layout

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

Science Camera

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

Calibration SystemPoster 9147-294 – Wednesday

(Marta Puga Antolín)An atmospheric turbulence and

telescope simulator for the development of AOLI

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

AOLI at the WHTThe initial run had four key aims:

1. To collect data from the nlCWFS for post-processing analysis and reconstruction.

2. To collect data using the science camera to verify its optical quality and sensitivity.

3. To collect synchronised data between the nlCWFS and science camera to allow comparison between reconstructed wavefronts and the science image.

4. To collect data with the calibration system to verify its characteristics against on-sky data.

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

AOLI at the WHT

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

AOLI at the WHT

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

On-sky data

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

On-sky data: Real-time lucky

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

On-sky data: Post processing

Velasco et al., 2014, MNRAS (In Prep)

Jonathan Crass - High-resolution imaging in the visible on large ground-based telescopes

Summary

• The combination of AO and lucky imaging allows diffraction limited imaging in the visible.

• The AOLI science camera data matches well with design specification.

• Issues experienced on first on-sky run identified and solutions implemented or proposed.

Summary & Future WorkFuture Work

• Redesign of some mechanisms and supports within instrument to improve performance.

• Fully develop AO system to provide diffraction limited imaging at the WHT.

• AOLI has the potential to feed not only an imaging camera but also an integral field spectrograph or other instruments.

• Aim to revisit the WHT in 2015.