HARMONI is the first light visible and near-IR integral field spectrograph for the ELT. In this paper we present an analysis of the performance of HARMONI’s SCAO system, based on a pyramid wavefront sensor operating in the I band. The impact of the telescope environment is examined, including windshake, primary mirror aberrations, and the dynamics and control of the ELT correctors (M4/M5). Optimisation of the control basis based on knowledge of the stress response of M4 is presented and the performance of secondary loops are analysed, including a low order loop for NCPA correction. Finally, a full end-to-end simulation of the HARMONI SCAO system is presented and compared with original error budgets.
MAVIS passed the Preliminary Design Review in March 2023 and kick started its phase C early June. We are aiming at a Final Design Review in December 2024. I will report on the state of MAVIS design, as well as general project updates, schedule, procurement, risks. We are working on early procurement (Long Lead Item review held on October 2023) as well as on a number of prototype activities I will report on.
Adaptive optics (AO) systems are crucial for high-resolution astronomical observations by compensating for atmospheric turbulence. While laser guide stars (LGS) address high-order wavefront aberrations, natural guide stars (NGS) remain vital for low-order wavefront sensing (LOWFS). Conventional NGS-based methods like Shack-Hartmann sensors have limitations in field of view, sensitivity, and complexity. Focal plane wavefront sensing (FPWFS) offers advantages, including a wider field of view and enhanced signal-to-noise ratio, but accurately estimating low-order modes from distorted point spread functions (PSFs) remains challenging. We propose an AI-powered FPWFS method specifically for low-order mode estimation in infrared wavelengths. Our approach is trained on simulated data and validated on on-telescope data collected from the Keck I adaptive optic (K1AO) bench calibration source in K-band. By leveraging the enhanced signal-to-noise ratio in the infrared and the power of AI, our method overcomes the limitations of traditional LOWFS techniques.This study demonstrates the effectiveness of AI-based FPWFS for low-order wavefront sensing, paving the way for more compact, efficient, and high-performing AO systems for astronomical observations.
REVOLT (Research, Experiment and Validation of Adaptive Optics with a Legacy Telescope) is an adaptive optics (AO) system on the 1.2-m telescope at the Herzberg Astronomy and Astrophysics Research Centre which is intended to demonstrate various AO developments, technologies, and algorithms. This AO system is a platform to test the Herzberg Extensible Adaptive optics Real-time Toolkit (HEART) where new AO control features can be exercised on-sky ahead of deployment on a facility class instrument. In this paper, we present various analysis of the telemetry produced by HEART and its various wavefront-sensing arms that enable both open- and closed-loop operation including a closed-loop Shack-Hartmann wavefront sensor, a closed-loop pyramid wavefront sensor, and an open-loop Shack-Hartmann. Employing REVOLT’s single-conjugate AO configuration, we look at extracting the Fried parameter and other atmospheric parameters from the telemetry and compare the results to an in-situ Ring Image Next Generation Scintillation Sensor (RINGSS) atmospheric seeing monitor and optical turbulence profiler. Finally, we discuss the AO system’s rejection-transfer function and overall system’s performance.
The Thirty Meter Telescope (TMT) will host three science instruments at first light: IRIS (InfraRed Imaging Spectrograph), WFOS (Wide Field Optical Spectrograph), and MODHIS (Multi-Objective Diffraction-limited Highresolution Infrared Spectrograph). IRIS is a workhorse imager and spectrograph coupled to the Narrow-Field InfraRed Adaptive Optics System (NFIRAOS) to exploit the gains possible when working at the diffraction limit on an extremely large telescope. It has an imager field of view of 34 by 34 square arcseconds, and the integral field spectrograph supports a variety of spaxel scales and fields of view at resolutions between 4000 and 10,000. MODHIS, also working behind NFIRAOS, is focused on exoplanet science will deliver precision radial velocity measurements at a spectral resolution of 100,000 for a single object. WFOS is the workhorse optical multi-object imaging spectrograph. It has an 8 by 3 square arcminute field of view and is capable of targeting almost 100 objects at once with resolutions between 1500 and 5000.
MAVIS (the MCAO-Assisted Visible Imager and Spectrograph), planned for the VLT Adaptive Optics Facility, represents an innovative step in Multi-Conjugate Adaptive Optics (MCAO) systems, particularly in its operation at visible wavelengths and anticipated contributions to the field of astronomical astrometry. Recognizing the crucial role of high-precision astrometry in realizing science goals such as studying the dynamics of dense starfields, this study focuses on the challenges of advancing astrometry with MAVIS to its limits, as well as paving the way for further enhancement by incorporating telemetry data as part of the astrometric analysis. We employ MAVISIM, Superstar, and DAOPHOT to simulate both MAVIS imaging performance and provide a pathway to incorporate telemetry data for precise astrometry with MAVIS. Photometry analyses are conducted using the Superstar and DAOPHOT platforms, integrated into a specifically designed pipeline for astrometric analysis in MCAO settings. Combining these platforms, our research aims to elucidate the impact of utilizing telemetry data on improving astrometric precision, potentially establishing new methods for ground-based AO-assisted astrometric analysis. This endeavor not only sheds light on the capabilities of MAVIS but also paves the way for advancing astrometry in the era of next-generation MCAO-enabled giant telescopes.
"We present initial results from the Multi-conjugate Adaptive-optics Visible Imager-Spectrograph Image Simulator (MAVISIM) to explore the astrometric capabilities of the next generation instrument MAVIS. A core scientific and operational requirement of MAVIS will be to achieve highly accurate differential astrometry, with accuracies on the order that of the extremely large telescopes. To better understand the impact of known and anticipated astrometric error terms, we have created an initial astrometric budget which we present here to motivate the creation of MAVISIM. In this first version of MAVISIM we include three major astrometric error sources; point spread function (PSF) field variability due to high order aberrations, PSF degradation and field variability due to tip-tilt residual error, and field distortions due to non-common path aberrations in the AO module. An overview of MAVISIM is provided along with initial results from a study using MAVISIM to simulate an image of a Milky Way-like globular cluster. Astrometric accuracies are extracted using PSF-fitting photometry with encouraging results that suggest MAVIS will deliver accuracies of 150µas down to faint magnitudes."
Laboratory Adaptive Optics (AO) benches are the backbone of experimental testing and verification of new AO designs and architectures. These testbeds are particularly important when exploring unknown factors in the development of new instruments and facilities like future extremely large telescope AO systems. One of the key elements for simulating the performance of such systems in a smaller scale laboratory environment is the ability of projecting the precise intensity mask on the pupil plane. This mask often has binary (black or transparent/reflective) patterns that mimic the secondary obscuration and spider design of the telescope. Precise implementation of such intensity masks on the bench is important since studying effects such as “island/petaling effect” are critically dependent on the correct down-scaling and precise representation of the spider structure. Using a physical mask for such an application is very difficult since manufacturing and installing such fine structure pieces are difficult and hard to use. It is also necessary to build a new physical mask for each telescope system or scale that is desired for the experiment. In this paper, we introduce two methods of using a phase only Liquid Crystal on Silicon Spatial Light Modulator (LCoS-SLM) device as an alternative option to precisely and relatively easily inject the custom intensity mask into an optical bench. By implementing these methods on the LOOPS bench AO facilities of the LAM, we demonstrated that the contrast produced by both methods could be better than 2% (dark/bright ratio), which is sufficient for representing pupil obscuration in the majority of applications. We also show that by using one of these methods, it is possible to inject phase and binary intensity mask simultaneously which could greatly increase the versatility and ease of use of an experimental AO setup.
The study of cold or obscured, red astrophysical sources can significantly benefit from adaptive optics (AO) systems employing infrared (IR) wavefront sensors. One particular area is the study of exoplanets around M-dwarf stars and planet formation within protoplanetary disks in star-forming regions. Such objects are faint at visible wavelengths but bright enough in the IR to be used as a natural guide star for the AO system. Doing the wavefront sensing at IR wavelengths enables high-resolution AO correction for such science cases, with the potential to reach the contrasts required for direct imaging of exoplanets. To this end, a new near-infrared pyramid wavefront sensor (PyWFS) has been added to the Keck II AO system, extending the performance of the facility AO system for the study of faint red objects. We present the Keck II PyWFS, which represents a number of firsts, including the first PyWFS installed on a segmented telescope and the first use of an IR PyWFS on a 10-m class telescope. We discuss the scientific and technological advantages offered by IR wavefront sensing and present the design and commissioning of the Keck PyWFS. In particular, we report on the performance of the Selex Avalanche Photodiode for HgCdTe InfraRed Array detector used for the PyWFS and highlight the novelty of this wavefront sensor in terms of the performance for faint red objects and the improvement in contrast. The system has been commissioned for science with the vortex coronagraph in the NIRC2 IR science instrument and is being commissioned alongside a new fiber injection unit for NIRSPEC. We present the first science verification of the system—to facilitate the study of exoplanets around M-type stars.
A future upgrade of the Keck II telescope’s adaptive optics system will include a near-infrared pyramid wavefront sensor. It will benefit from low-noise infrared detector technology, specifically the avalanche photodiode array SAPHIRA (Leonardo). The system will either operate with a natural guide star in a single conjugated adaptive optics system, or using a laser guide star (LGS), with the pyramid working as a low-order sensor. We present a study of the pyramid sensor’s performance via end-to-end simulations, including an analysis of calibration strategies. For LGS operation, we compare the pyramid to LIFT, a focal-plane sensor dedicated to low-order sensing.
A near-infrared, high order pyramid wavefront sensor will be implemented on the Keck telescope, with the aim of providing high resolution adaptive optics correction for the study of exoplanets around M-type stars and planet formation in obscured star forming regions. The pyramid wavefront sensor is designed to support adaptive optics correction of the light to an imaging vortex coronagraph and to a fiber injection unit that will feed a spectrograph. We present the opto-mechanical design of the near-infrared pyramid wavefront sensor, the optical performance, and the alignment strategy. The challenges of designing the assembly, as well as a fiber injection unit, to fit into the limited available space on the Keck adaptive optics bench, will also be discussed.
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