Ingot Laser Guide Stars Wavefront Sensing

Ragazzoni, Roberto; Portaluri, Elisa; Viotto, Valentina; Dima, Marco; Bergomi, Maria; Biondi, Federico; Farinato, Jacopo; Carolo, Elena; Chinellato, Simonetta; Greggio, Davide; Gullieuszik, Marco; Magrin, Demetrio; Marafatto, Luca; Vassallo, Daniele

doi:10.26698/ao4elt5.0096

Cited by 6 publications

(6 citation statements)

References 7 publications

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“…Wavefront sensing is achieved in a cooperative manner on both the artificial LGS and the (eventually in the Field of View) NGSs. The first are sensed using a reflective roof ingot-like approach [15] and we depicted in Fig.2 a possible layout for their arrangement. As the LGSs are monochromatic, their light is collected and folded by a dichroic and the WFSs are mounted on radially movable (to follow the different range of the LGSs because of the different altitude of the telescope) and tiltable (in order to match the equivalent optical length of the LGSs on the ingots).…”

Section: Segmenting the Field Of Viewmentioning

confidence: 99%

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Hierarchichal-segmented AO in order to attain wide field compensation in the visible on an 8m class telescope.

Ragazzoni¹,

Magrin²,

Farinato³

et al. 2017

Proceedings of the Adaptive Optics for Extremely Large Telescopes 5

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We describe the preliminary optimized layout for a partially optimized concept of an optical-8m class VLT-like 2x2 segmented camera where each channel is assisted by an equivalent of an MCAO system where the ground layer correction is commonly employed while the high altitude ones is performed in an open-loop fashion. While we derive the basic relationships among the Field of View and attainable correction with a pre-defined choice for the hardware, we discuss sky coverage and wavefront sensing issues employing natural and artificial references, involving the latest stateof-the-art in the development of wavefront sensing. We show that a flexible approach allow for a compensated Field of View that is variable and can be properly tuned matching the current turbulence situation and the requirement in term of quality of the compensation. A preliminary description of the overall optomechanical package is given as well along with a rough estimates of the efforts required to translates such a concept into reality.

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Section: Segmenting the Field Of Viewmentioning

confidence: 99%

Section: Segmenting the Field Of Viewmentioning

confidence: 99%

Hierarchichal-segmented AO in order to attain wide field compensation in the visible on an 8m class telescope.

Ragazzoni¹,

Magrin²,

Farinato³

et al. 2017

Proceedings of the Adaptive Optics for Extremely Large Telescopes 5

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“…The Ingot wavefront sensor (I-WFS), has been proposed in the ELT MAORY framework, as alternative to the classical concept of wavefront sensor, to cope with the typical elongation of the Laser Guide Star (LGS). 1 This effect, is due to the intrinsic nature of the Sodium layer, which is located at about 90 km of altitude in atmosphere and extended for approximately 10 km. This layer, not only has a certain thickness, but also a certain density distribution, both varying in time.…”

Section: Introductionmentioning

confidence: 99%

INGOT Wavefront Sensor: from the optical design to a preliminary laboratory test

Di Filippo,

Greggio,

Bergomi

et al. 2021

Preprint

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The Ingot wavefront sensor is a novel pupil-plane wavefront sensor, specifically designed to cope with the elongation typical of the extended nature of the Laser Guide Star (LGS). In the framework of the ELT, we propose an optical solution suitable for a Laser launch telescope, located outside the telescope pupil. In this paper, we present the current optical design, based on a reflective roof-shaped prism, which, at the level of the focal plane, splits the light from an LGS producing three beams. The three images of the telescope pupils can be then used for the retrieval of the first derivative of the wavefront. The 3D nature of such a device requires new alignment techniques to be determined theoretically and verified in the real world. A possible fully automated procedure, relying solely on the illumination observed at the three pupils, to align the prism to the image of the LGS is discussed. Careful attention needs to be put both on the telecentricity of the system and on the reference systems of the Ingot adjustments in the 3D space. This is crucial in order to disentangle all the possible misalignment effects. In this context, we devised a test-bench able to reproduce, in a scaled manner, the 3D illumination that the Ingot will face at the ELT, in order to validate the design and to perform preliminary tests of phase retrieval.

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“…6 This layer, not only has a specific thickness, but also a particular vertical density distribution, both varying spatially and temporally. 7 The Ingot Wavefront Sensor (I-WFS), 8 has been designed to cope with this typical elongation of the LGS and presented as novel pupil-plane wavefront sensor in the framework of the Extremely Large Telescope 9 (ELT) project. The LGS produces a significant elongation on many of the Shack-Hartmann wavefront sensor (SH-WFS) spots, especially for large telescopes.…”

Section: Introductionmentioning

confidence: 99%

“…It has been tested at the LAM-ONERA On-sky Pyramid Sensor LOOPS 11 bench at Laboratoire d'Astrophysique de Marseille (LAM), in a quasi-real Adaptive Optics (AO) system using two Spatial Light Modulators (SLM) for the generation of the two-dimensional phase mask representing the I-WFS faces and, separately, the phase screen and the corrector (working as a deformable mirror). For more and further details about the I-WFS, we direct the reader to the original papers 8,12,13 and further developments. [14][15][16][17][18] In section 2 we describe the I-WFS, in section 4 the LOOPS bench setup, in section 3 we introduce the numerical tool used to produce the simulation presented in section 5 and discussed in section 6.…”

Section: Introductionmentioning

confidence: 99%

Ingot wavefront sensor: from the Fourier End2End numerical simulation to the LOOPS test bench

Arcidiacono¹,

Filippo²,

Greggio³

et al. 2020

Adaptive Optics Systems VII

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The Sodium Laser Guide Star (LGS) is an elongated object in a 3D volume. This produces a significant elongation on many of the Shack-Hartmann wavefront sensor spots that the ELT instruments use for wavefront sensing. The Ingot Wavefront Sensor (I-WFS) has been proposed as a possible solution to deal with the 3D nature of the LGS. We developed an end-to-end numerical tool of the I-WFS to perform system analysis of a closed-loop complete system. We considered the generation of the input turbulence, deformable mirror definition and control, and, of course details, of the I-WFS. It needs a 3-Dimensional description to fully take into account the elongation effect across the vertical (propagation) axis. The I-WFS has been simulated similarly to the Pyramid Wavefront Sensor, as a combination of Foucault knife-edge sensors. In parallel to numerical simulations development, we had the opportunity to perform laboratory testing of the I-WFS at the LOOPS Adaptive Optics test bench (at LAM), using a Spatial Light Modulator. This device is able to produce a high definition phase mask that can mimic two-dimensional I-WFS behaviour. In this framework, we report a preliminary discussion both for the simulations and the closed-loop data analysis.

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Ingot Laser Guide Stars Wavefront Sensing

Cited by 6 publications

References 7 publications

Hierarchichal-segmented AO in order to attain wide field compensation in the visible on an 8m class telescope.

Hierarchichal-segmented AO in order to attain wide field compensation in the visible on an 8m class telescope.

INGOT Wavefront Sensor: from the optical design to a preliminary laboratory test

Ingot wavefront sensor: from the Fourier End2End numerical simulation to the LOOPS test bench

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