the adaptive optics lucky imager high-resolution imaging in the visible on large ground-based...
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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.