57 research outputs found
Super-resolution wavefront reconstruction
Super-Resolution (SR) is a technique that seeks to upscale the resolution of
a set of measured signals. SR retrieves higher-frequency signal content by
combining multiple lower resolution sampled data sets. SR is well known both in
the temporal and spatial domains. It is widely used in imaging to reduce
aliasing and enhance the resolution of coarsely sampled images.This paper
applies the SR technique to the bi-dimensional wavefront reconstruction. In
particular, we show how SR is intrinsically suited for tomographic multi
WaveFront Sensor (WFS) AO systems revealing many of its advantages with minimal
design effort. This paper provides a direct space and Fourier-optics
description of the wavefront sensing operation and demonstrate how SR can be
exploited through signal reconstruction, especially in the framework of
Periodic Nonuniform Sampling. Both meta uniform and nonuniform sampling schemes
are investigated. Then, the SR bi-dimensional model for a Shack Hartmann (SH)
WFS is provided and the characteristics of the sensitivity function are
analyzed. The SR concept is finally validated with numerical simulations of
representative multi WFS SH AO systems. Our results show that combining several
WFS samples in a SR framework grants access to a larger number of modes than
the native one offered by a single WFS and that despite the fixed sub-aperture
size across samples. Furthermore, we show that the associated noise propagation
is not degraded under SR. Finally, the concept is extended to the signal
produced by single Pyramid WFS. In conclusion, SR applied to wavefront
reconstruction offers a new parameter space to explore as it decouples the size
of the subaperture from the desired wavefront sampling resolution. By cutting
short with old assumptions, new, more flexible and better performing AO designs
become now possible.Comment: Astronomy & Astrophysics Section: 13. Astronomical instrumentation
AA/2022/4395
Non-modulated pyramid wavefront sensor: Why, how and when to use it to sense and correct atmospheric turbulence
Context. The diffusion of adaptive optics systems in astronomical
instrumentation for large ground based telescopes is rapidly increasing and the
pyramid wavefront sensor is replacing the Shack-Hartmann as standard solution
for single conjugate adaptive optics systems. The pyramid wavefront sensor is
typically used with a tip/tilt modulation to increase the linearity range of
the sensor, but the non-modulated case is interesting because it maximizes the
sensor sensitivity. The latter case is generally avoided for the reduced
linearity range that prevents robust operation in the presence of atmospheric
turbulence.
Aims. We aim to solve part of the issues of the non-modulated pyramid
wavefront sensor by reducing the model error in the interaction matrix. We
linearize the sensor response in the working conditions without extending the
sensor linearity range.
Methods. We introduce a new calibration approach to model the response of
pyramid wave front sensor in partial correction, where the working conditions
in the presence of residual turbulence is considered.
Results. We show how in simulations, through the new calibration approach,
the pyramid wave front sensor without modulation can be used to sense and
correct atmospheric turbulence and when this case is preferable to the
modulated case.Comment: 12 pages with 18 figures; accepted for publication in A&
The numerical simulation tool for the MAORY multiconjugate adaptive optics system
The Multiconjugate Adaptive Optics RelaY (MAORY) is and Adaptive Optics
module to be mounted on the ESO European-Extremely Large Telescope (E-ELT). It
is a hybrid Natural and Laser Guide System that will perform the correction of
the atmospheric turbulence volume above the telescope feeding the Multi-AO
Imaging Camera for Deep Observations Near Infrared spectro-imager (MICADO). We
developed an end-to-end Monte- Carlo adaptive optics simulation tool to
investigate the performance of a the MAORY and the calibration, acquisition,
operation strategies. MAORY will implement Multiconjugate Adaptive Optics
combining Laser Guide Stars (LGS) and Natural Guide Stars (NGS) measurements.
The simulation tool implements the various aspect of the MAORY in an end to end
fashion. The code has been developed using IDL and uses libraries in C++ and
CUDA for efficiency improvements. Here we recall the code architecture, we
describe the modeled instrument components and the control strategies
implemented in the code.Comment: 6 pages, 1 figure, Proceeding 9909 310 of the conference SPIE
Astronomical Telescopes + Instrumentation 2016, 26 June 1 July 2016
Edinburgh, Scotland, U
MAORY AO performances
The Multi-conjugate Adaptive Optics RelaY (MAORY) should provide 30% SR in K
band (50% goal) on half of the sky at the South Galactic Pole. Assessing its
performance and the sensitivity to parameter variations during the design phase
is a fundamental step for the engineering of such a complex system. This step,
centered on numerical simulations, is the connection between the performance
requirements and the Adaptive Optics system configuration. In this work we
present MAORY configuration and performance and we justify theAdaptive Optics
system design choices.Comment: 9 pages, 7 figures, 1 table. SPIE conference Astronomical Telescopes
and Instrumentation, 14 - 18 December 2020, digital foru
Overview of AO calibration strategies in the ELT context
The scientific potential of the ELT will rely on the performance of its AO systems that will require to be perfectly calibrated before and during the operations. The actual design of the ELT will provide a constraining environment for the calibration and new strategies have to be developed to overcome these constraints. This will be particularly true concerning the Interaction Matrix of the system with no calibration source upward M4 and moving elements in the telescope. After a brief presentation of the ELT specificities for the calibration, this communication focuses on the different strategies that have already been developed to get/measure the Interaction Matrix of the system, either based on synthetic models or using on-sky measurements. First tests of these methods have been done using numerical simulations for a simple AO system and a proposition for a calibration strategy of the ELT will be presented
The MAORY laser guide star wavefront sensor: design status
MAORY will be the multi-adaptive optics module feeding the high resolution camera and spectrograph MICADO at the Extremely Large Telescope (ELT) first light. In order to ensure high and homogeneous image quality over the MICADO field of view and high sky coverage, the baseline is to operate wavefront sensing using six Sodium Laser Guide Stars. The Laser Guide Star Wavefront Sensor (LGS WFS) is the MAORY sub-system devoted to real-time measurement of the high order wavefront distortions. In this paper we describe the MAORY LGS WFS current design, including opto-mechanics, trade-offs and possible future improvements
MORFEO enters final design phase
MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations, formerly
MAORY), the MCAO system for the ELT, will provide diffraction-limited optical
quality to the large field camera MICADO. MORFEO has officially passed the
Preliminary Design Review and it is entering the final design phase. We present
the current status of the project, with a focus on the adaptive optics system
aspects and expected milestones during the next project phase
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