As the new generation of telescopes is coming soon, we need to solve or improve some issues related to the adaptive optics techniques, necessary to fully exploit their extraordinary capabilities in terms of sensitivity and resolution. The Ingot wavefront sensor was thought to overcome some limitations due to the use of artificial sources instead of natural ones: it is designed to cope with the typical elongation of Sodium Laser Guide stars that will be used by the ELTs. Here we present the preliminary tests we performed to properly set up an end-to-end simulator, in order to evaluate the performance of such a device. We describe the different configurations considered and the assumptions we made, discussing also some computational problems we faced building up the tool. We also show the results of the first simulations obtained closing the loop with a mock ELT telescope.
A consortium of several Australian and European institutes – together with the European Southern Observatory (ESO) – has initiated the design of MAVIS, a Multi-Conjugate Adaptive Optics (MCAO) system for the ground- based 8-m Very Large Telescope (VLT). MAVIS (MCAO-assisted Visible Imager and Spectrograph) will deliver visible images and integral field spectrograph data with 2-3x better angular resolution than the Hubble Space Telescope, making it a powerful complement at visible wavelengths to future facilities like the space-based James Webb Space Telescope and the 30 to 40m-class ground-based telescopes currently under construction, which are all targeting science at near-infrared wavelengths. MAVIS successfully passed its Phase A in May 2020. We present the motivations, requirements, principal design choices, conceptual design, expected performance and an overview of the exciting science enabled by MAVIS.
Despite the ability to remove the degradation introduced by the atmospheric turbulence has dramatically improved in the last years, in particular for NGS based systems, sky-coverage is one of the major issues for ground-based observations with current and future AO-assisted telescopes. Although new LGS WFS concepts have been recently proposed to strongly improve performances, the use of LGS, to increase the limited sky-coverage, still remains a significant bottleneck, severely limiting the exploitation of the enormous capabilities of current and already planned AO instrumentation on the 8-10m class telescopes and the upcoming ELTs. The progressive advancement of AO and the advent of CubeSat technologies, have led to the possibility of providing the largest ground-based AO facilities with suitable Satellite Guide Stars (SGS) as reference, to overcome the sky-coverage problem and achieve unprecedented scientific results. This perspective has induced numerous research institutes around the world to collaborate and to propose new ambitious space programs. The Ground-based adaptive optics Observations with Orbiting Nanosatellite (GO-ON) mission aims to design, develop and launch a CubeSat pathfinder, to assist astronomical observations at the Large Binocular Telescope (LBT). This mission will demonstrate, for the first time, the readiness of space and ground-based technologies and validate this new paradigm for future scientific programs with the ELTs, enabling transformative science across many fields of astrophysics.
MAORY is the MCAO module for the ELT. It feeds MICADO and a still to be defined second port instrument. The ”Science Operation” Working Group of MAORY focuses the activity on the simulation of the science cases proposed for the instrument, deriving in this way the achievable performance in different observing conditions, as can be the case of a crowded globular cluster or an almost star-empty frame on a high-z target. In this paper, we discuss the recent activities of the WP focusing on the numerical simulations environment we built and on the contribution to the Operational Concept Description of MAORY.
The MCAO Assisted Visible Imager and Spectrograph (MAVIS) is a facility-grade visible MCAO instrument, currently under development for the Adaptive Optics Facility at the VLT. The adaptive optics system will feed both an imager and an integral field spectrograph, with unprecedented sky coverage of 50% at the Galactic Pole. The imager will deliver diffraction-limited image quality in the V band, cover a 30" x 30" field of view, with imaging from U to z bands. The conceptual design for the spectrograph has a selectable field-of-view of 2.5" x 3.6", or 5" x 7.2", with a spatial sampling of 25 or 50 mas respectively. It will deliver a spectral resolving power of R=5,000 to R=15,000, covering a wavelength range from 380 - 950 nm. The combined angular resolution and sensitivity of MAVIS fill a unique parameter space at optical wavelengths, that is highly complementary to that of future next-generation facilities like JWST and ELTs, optimised for infrared wavelengths. MAVIS will facilitate a broad range of science, including monitoring solar system bodies in support of space missions; resolving protoplanetary- and accretion-disk mechanisms around stars; combining radial velocities and proper motions to detect intermediate-mass black holes; characterising resolved stellar populations in galaxies beyond the local group; resolving galaxies spectrally and spatially on parsec scales out to 50 Mpc; tracing the role of star clusters across cosmic time; and characterising the first globular clusters in formation via gravitational lensing. We describe the science cases and the concept designs for the imager and spectrograph.
MAORY is a post-focal adaptive optics module that forms part of the first light instrument suite for the ELT. The main function of MAORY is to relay the light beam from the ELT focal plane to the client instrument while compensating the effects of the atmospheric turbulence and other disturbances affecting the wavefront from the scientific sources of interest.
The point spread function reconstruction (PSF-R) capability is a deliverable of the MICADO@ESO-ELT project. The PSF-R team works on the implementation of the instrument software devoted to reconstruct the point spread function (PSF), independently of the science data, using adaptive optics (AO) telemetry data, both for Single Conjugate (SCAO) and Multi-Conjugate Adaptive Optics (MCAO) mode of the MICADO camera and spectrograph. The PSF-R application will provide reconstructed PSFs through an archive querying system to restore the telemetry data synchronous to each science frame that MICADO will generate. Eventually, the PSF-R software will produce the output according to user specifications. The PSF-R service will support the state-of-the-art scientific analysis of the MICADO imaging and spectroscopic data.
The Sodium Laser Guide Star (Na-LGS) on the sky is not point-like, rather cigar-like when launched from the side of a large (or extremely large) telescope. The Na-LGS’s 3D nature gave birth to the idea of a new pupil-plane wavefront sensor that can be deployed in a similar 3D manner - the Ingot Wavefront Sensor (I-WFS). The design of the I-WFS has developed over the last two years, and currently, the ingot prism has 3-faces, creating three pupils. Wavefront sensing can be done using these three pupils themselves as the signals or the slopes generated by the pupils. At the INAF-Padova laboratory, we have realized a test-bench simulating the ELT∗ characteristics to test the I-WFS characteristics and an alignment procedure. We use simulations and lab data to compare, learn, and define a robust alignment procedure. Eventually, we expect to have an entirely automatized alignment procedure using the optical feedback from the I-WFS. In this article, we report the comparison between the laboratory data and the simulations representing (1) the sensitivity measurements of ingot prism misalignment for each degree of freedom with respect to its ideal, aligned position, and (2) the response of the I-WFS to known aberrations using a deformable lens. The final goal is the definition and description of the procedure to align the I-WFS.
SHARK-NIR in an instrument that will provide direct imaging, coronagraphic imaging, dual band imaging and low resolution spectroscopy in Y, J and H bands, and it will be soon installed at the Large Binocular Telescope. Used in combination with SHARK-VIS (operating in V band) and LMIRCam of LBTI (operating from K to M bands), SHARKNIR will exploit coronagraphic simultaneous observations in three different wavelengths. Exoplanets search and characterization, young stellar systems, jets and disks are the main science cases, but the extreme performance of the LBT AO systems, above all in the faint end regime, will allow to open to science difficult to be achieved from other similar instruments, such as AGN and QSO morphological studies. A variety of coronagraphic techniques have been implemented, as the Gaussian Lyot, Shaped Pupil and Four Quadrant masks, with the aim to possibly have a suitable coronagraphic masks for each science case, since the coronagraphic requirement in term of contrast and inner and outer working angle are depending on the target and on the science to be achieved. We report here about the SHARK-NIR status, that should be installed at LBT in mid-2021
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.
CHEOPS (CHaracterizing ExOPlanets Satellite) is an ESA Small Mission, planned to be launched in early 2019 and whose main goal is the photometric precise characterization of the radii of exoplanets orbiting bright stars (V<12) already known to host planets. The telescope is composed by two optical systems: a compact on-axis F/5 Ritchey-Chrétien, with an aperture of 320 mm and a Back-End Optics, reshaping a defocused PSF on the detector. In this paper we describe how alignment and integration, as well as ground support equipment, realized on a demonstrator model at INAF Padova, evolved and were successfully applied during the AIV phase of the flight model telescope subsystem at LEONARDO, the Italian industrial prime contractor premises.
SHARK-NIR is one of the forthcoming instruments of the Large Binocular Telescope second generation instruments. Due to its coronagraphic nature, coupled with low resolution spectroscopy capabilities, it will be mainly devoted to exoplanetary science, but its FoV of 18 x 18 arcsec and very high contrast imaging capabilities will allow to exploit also other intriguing scientific cases. The instrument has been conceived and designed to fully exploit the exquisite adaptive optics correction delivered by the FLAO module, which will be improved with the SOUL upgrade, and will implement different coronagraphic techniques, with contrast as high as 10-6 up to 65 mas from the star. Despite the wavelength range of SHARK-NIR is 0.96-1.7 um, the instrument is designed to work in synergy with SHARK-VIS and with LMIRcam, on board of LBTI. The contemporary acquisition from these instruments will extend the wavelength coverage from M band down to the visible radiation. The physical location of the instrument, at the entrance of LBTI, imposes dimensional constraints to the instrument, which had been kept very compact. The folded optical design includes more than 50 optical elements, among which 4 Off-Axis Parabolas, 1 Deformable Mirror for the compensation of the Non Common Path Aberrations from the FLAO Wavefront Sensor, 2 detectors and 3 different kinds of coronagraph: Gaussian Lyot, Shaped Pupil and Four Quadrant Pupil Mask. Most of these optics are located onto an optical bench 500 x 400 mm, which makes SHARK-NIR an extremely dense instrument. This, together with the presence of 4 off-axis parabolas and of coronagraphs, such as the Four Quadrant, poorly tolerant to misalignments, requires a careful alignment and test phase, which needs the fine adjustement of many hundreds of degrees of freedom. We will give here an overview of the opto-mechanical layout of SHARK-NIR and of the identified alignment procedure, mostly optical, planned to take place in 2018.
Laser Guide Stars are, in spite of their name, all but “stars”. They do not stand at infinite distance, neither on a plane. If fired from the side of a large telescope their characteristics as seen from various points on the apertures changes dramatically. As they extend in a 3D world, there is need of a WFS that deploy in a similar 3D manner, in the conjugated volume, resembling the approach that MCAO required long time ago to overcome the usual limitations of conventional AO. We describe a class of a novel kind of WFS that employ a combination of refraction and reflection, such that they can convey the light from an LGS into a limited number of pupils, making the device compact, doable with a single piece of glass, and able to feed a minimum sized format detector where the information is collected maximizing the information depending from which part of the LGS the light is coming from, and on which portion of the telescope aperture the light is landing. They represent, in our opinion, the best-known adaptation of the pyramid WFS for NGS to the LGS world. As in the natural reference case the practical advantages come along with some fundamental advantages. Being a pupil plane WFS with the perturbator placed on the (3D) loci of focus of the various portions of the source of light they have the potentiality to extend WFS to a number of issues, including the ability to sense the islands effect, where non-contiguous portions of the main apertures are optically displaced. Further to their description and the main recipes we speculate onto possible variations on cases where the LGS is fired from the back of the secondary mirror and we exploit some potential features when implementing onto an extremely large aperture.
As LGSs come from an excited cigar-shaped region in the sodium layer, they do not behave as point-like sources, therefore a new class of WFSs has been proposed to account for such elongation: the Ingot WFSs, the LGS-counterpart of a pyramid WFS. As they appear to be very promising, here we summarize the main reasons and goal of such a LGS-dedicated WFS and present the concept behind the code developed to produce numerical simulations, exploring the space of parameters. We report different approaches for the approximation of the extended source and the model adopted for the ingot prism simulation.
As the deep field surveys strategy represents a well popular way to study the cosmology and the formation and evolution of galaxies, we investigated how the new generation of extremely large telescopes (ELTs) will perform in this field of research. Our simulations, which combine a number of technical, tomographic and astrophysical information, take advantages of the Global-MCAO approach, a well demonstrated method that can be applied in absence of laser guide stars because it exploits only natural references. A statistics of the expected performance in a sub-sample of 22 well-known surveys are presented here.
We present a new testing facility hosted at the Coude focus of the INAF-Padova Copernico Telescope, a project carried on within the ADaptive Optics National Italian laboratories - ADONI. A permanent laboratory for on-sky experimentation accessible to the AO community, with the aim of hosting visiting multi-purpose instrumentation that may be directly tested on sky. We will give an overview of the activities carried on, describing the refurbishment activities at the hosting structure that allowed the opening of the facility: the implementation of the opto-mechanical train down to the Coude focus, and the creation of the laboratory. This facility provides a powerful scientific and technical test bench for new instrumental concepts, which may eventually be incorporated later in the next generation ELTs telescopes.
SHARK-NIR is a coronagraphic camera that will be implemented at the Large Binocular Telescope. SHARK-NIR will offer extreme AO direct imaging capability on a field of view of about 18" x 18", and a simple coronagraphic spectroscopic mode offering spectral resolution ranging from 100 to 700. In order to meet the SHARK-NIR main scientific driver, i.e., searching for giant planets on wide orbits, a high contrast is necessary. A set of corona-graphic masks were tested, we selected the best performing configurations for the instrument: the Gaussian-Lyot coronagraph, a Shaped Pupil (SP) with 360° of discovery space and two SP masks with asymmetric detection area but with a small inner working angle and the Four Quadrant phase mask. Many simulations were performed to obtain the performance in different atmospheric conditions, including seeing variations, by using magnitude guide star from R = 8 to R = 14 and testing also the jitter value. These changes in simulation parameters reflected a variation in the corona-graphic performance. We analysed the simulation images by searching the best post processing to obtain the best performance for the coronagraph, moreover, we have taken account the fact that using, in the ADI technique, small subsets to generate the reference PSF can help attenuating the speckle noise, but it also results in a growing risk of planet removal if not enough field rotation occurs in the subset itself. We analysed the results after this effect is included, so the performances were shown as function of the Strehl Ratio condition to obtain mass and age limits for the detection of the planets.
PLATO (PLAnetary Transits and Oscillation of stars) is the ESA Medium size dedicated to exo-planets discovery, adopted in the framework of the Cosmic Vision program. The PLATO launch is planned in 2026 and the mission will last at least 4 years in the Lagrangian point L2. The primary scientific goal of PLATO is to discover and characterize a large amount of exo-planets hosted by bright nearby stars, constraining with unprecedented precision their radii by mean of transits technique and the age of the stars through by asteroseismology. By coupling the radius information with the mass knowledge, provided by a dedicated ground-based spectroscopy radial velocity measurements campaign, it would be possible to determine the planet density. Ultimately, PLATO will deliver the largest samples ever of well characterized exo-planets, discriminating among their ‘zoology’. The large amount of required bright stars can be achieved by a relatively small aperture telescope (about 1 meter class) with a wide Field of View (about 1000 square degrees). The PLATO strategy is to split the collecting area into 24 identical 120 mm aperture diameter fully refractive cameras with partially overlapped Field of View delivering an overall instantaneous sky covered area of about 2232 square degrees. The opto-mechanical sub-system of each camera, namely Telescope Optical Unit, is basically composed by a 6 lenses fully refractive optical system, presenting one aspheric surface on the front lens, and by a mechanical structure made in AlBeMet.
PLATO (Planetary Transits and Oscillations of stars) is a new space telescope selected by ESA to detect terrestrial exoplanets in nearby solar-type stars. The telescope is composed by 26 small telescopes to achieve a large instantaneous field of view. INAF-OAPD is directly involved in the optical design and in the definition and testing of the alignment strategy. A prototype of the Telescope Optical Unis (TOU) was assembled and integrated in warm condition (room temperature) and then the performance is tested in warm and cold temperature (-80C). The mechanical structure of the TOU is representative in terms of thermal expansion coefficient and Young's modulus with respect to the actual one. A dedicated GSE (Ground Support Equipment) is used to manipulate the lenses. By co-align an interferometer and a laser with respect to the center of the third CaF2 lens, a several observables references are used to define the position and tilt of the chief ray. The total procedure tolerances for every lens is 30'' in tilt, between 15-40 μm for focus and 22 μm for decentering and the total error budget of the optical setup bench is below this requirement. In this paper, we describe the AIV procedure and test performed on the prototype of the TOU in the INAF laboratory.
CHEOPS (CHaracterizing ExOPlanets Satellite) is an ESA Small Mission, planned to be launched in mid-2018 and
whose main goal is the photometric precise characterization of radii of exoplanets orbiting bright stars (V<12) already
known to host planets.
Given the fast-track nature of this mission, we developed a non-flying Demonstration Model, whose optics are flight
representative and whose mechanics provides the same interfaces of the flight model, but is not thermally representative.
In this paper, we describe CHEOPS Demonstration Model handling, integration, tests, alignment and characterization,
emphasizing the verification of the uncertainties in the optical quality measurements introduced by the starlight simulator
and the way the alignment and optical surfaces are measured.
In the context of ADONI, the newly constituted laboratory for INAF Adaptive Optics activities, it is foreseen to set-up a facility accessible to the Italian and international AO community, with the purpose of facilitating the testing of critical sub-systems or components (which may be part of instruments under construction), or prototypes of innovative concepts which may require on-sky demonstrations. The 182cm Copernico Telescope located in Asiago (Italy) has been selected to be a suitable place to set-up this public facility, where a common optical bench will be made available at the Coudé focus to host visiting instrumentation. In this paper we describe the opto-mechanical train to the Coudé focal station to be implemented for the laboratory set-up, and we sketch out the foreseen telescope refurbishing activities to implement this multi-purpose testing facility dedicated to AO related projects.
In the last years, the Pyramid WFS finally proved itself to be a very powerful tool for wavefront retrieval, in different applications, inside and outside Astronomy, often showing outstanding results. However, being intrinsically a non-linear WFS, the P-WFS non-linearity error starts to play a role when the AO loop is not closed on the sensor zero-WFE point. This led to the need to elaborate new concepts when trying to apply the P-WFS to open (or partially open) loop based techniques, not to trade sensitivity for linearity. This was the case for GMCAO, in which the reference stars are selected on a wide technical area of the sky, outside the FoV to be optimized, limiting the correction experienced by the WFSs to poor Strehl Ratio regime. While, in the recent past, we proposed a solution based on the Very Linear WFS, a sub-system that locally closes the loop on the Pyramid pin to let the sensor operate in its best regime, we now explore a different approach in which the P-WFS non-linearity is continuously measured, injecting a known aberration onto the sensor. In particular, we evaluate in this paper the possibility to apply basic PWFSs to the GMCAO technique, measuring the nonlinearity of the sensor and taking it into account in the wavefront computation, with an approach similar to what already proposed in the LBT AO facility FLAO for the non-common path aberrations correction.
Global-Multi Conjugate Adaptive Optics (GMCAO) can be a reliable approach for the new generation of Extremely Large Telescopes (ELTs) to address the issue of the sky coverage. It is based on the idea of using the largest possible technical field-of-view, to maximize the chance to find suitable reference stars. To prove that such innovative concept is robust and can be successfully used for studying faint objects, we build mock images of high-z galaxies and analyze them as if they were real and observed with an ELT that benefits of GMCAO. The results we obtained from the analysis of these images claim that this kind of method can be well used for extragalactic deep surveys, a key instrument that next generation telescopes will use to understand the origin and the evolution of galaxies.
In this work we discuss some options for using Unmanned Aerial Vehicles (UAVs) for daylight alignment activities and maintenance of optical telescopes, relating them to a small numbers of parameters, and tracing which could be the schemes, requirements and benefits for employing them both at the stage of erection and maintenance. UAVs can easily reach the auto-collimation points of optical components of the next class of Extremely Large Telescopes. They can be equipped with tools for the measurement of the co-phasing, scattering, and reflectivity of segmented mirrors or environmental parameters like C2n and C2T to characterize the seeing during both the day and the night.