We describe the motivation, design, and early results for our 42-night, 125 star Subaru/SCExAO direct imaging survey for planets around accelerating stars. Unlike prior large surveys, ours focuses only on stars showing evidence for an astrometric acceleration plausibly due to the dynamical pull of an unseen planet or brown dwarf. Our program is motivated by results from a recent pilot program that found the first planet jointly discovered from direct imaging and astrometry and resulted in a planet and brown dwarf discovery rate substantially higher than previous unbiased surveys like GPIES. The first preliminary results from our program reveal multiple new companions; discovered planets and brown dwarfs can be further characterized with follow-up data, including higher-resolution spectra. Finally, we describe the critical role this program plays in supporting the Roman Space Telescope Coronagraphic Instrument, providing a currently-missing list of targets suitable for the CGI technological demonstration without which the CGI tech demo risks failure.
Directly imaging habitable-zone exoplanets and obtaining their spectra is a central goal in exoplanet science, but is extremely challenging due to the high contrasts and small angular separations which must be achieved. Nulling interferometry is a solution which suppresses on-axis starlight through destructive interference such that the star is ‘nulled out’. The Guided Light Interferometric Nulling Technology Instrument (GLINT) at the 8.2-meter Subaru telescope performs nulling interferometry using waveguides and couplers within a photonic chip, and will provide generalisable insights that are applicable to future nullers. However, to produce high starlight suppression and deeper nulls, correcting seeing-induced wavefront error is of paramount importance. Here we present the design for the real-time control loop of the GLINT instrument which performs fringe tracking and active fringe modulation to correct wavefront errors. To allow for user interaction, the control loop is encapsulated within a graphical user interface, enabling manual, automatic, and simulated functionality, and it utilises the MILK framework for high speed data acquisition and control.
GLINT is a nulling interferometer downstream of the SCExAO extreme-adaptive-optics system at the Subaru Telescope (Hawaii, USA), and is a pathfinder instrument for high-contrast imaging of circumstellar environments with photonic technologies. GLINT is effectively a testbed for more stable, compact, and modular instruments for the era of ∼30m-class telescopes. GLINT is now undergoing an upgrade with a new photonic chip for more achromatic nulls, and for phase information to enable fringe tracking. Here we provide an overview of the motivations for the GLINT project and report on the design of the new chip, the on-site installation, and current status.
The technique of nulling interferometry is helping to overcome the challenges of directly detecting exoplanets and is the foundation for the Guided Light Interferometric Nulling Technology (GLINT) instrument located at the Subaru telescope in Hawaii. A new integrated optics beam combiner will be deployed to simultaneously perform nulling interferometry and fringe tracking. This is enabled by using a photonic device called a tricoupler. Comprising of 3 input single-mode waveguides, the tricoupler produces 3 outputs, consisting of the interferometric nulled output and two phase-sensitive bright outputs.
These 3D waveguide tricouplers are fabricated using the femtosecond laser direct-write technique. This process involves a tightly focused laser to modify the refractive index of a boro-aluminosilicate glass sample, creating optical waveguides. We present a rigorous optimisation of the tricouplers which includes a numerical solution to coupled-mode equations to obtain coupling coefficients and propagation constants that are used to optimise the fabrication process for the J (1.1 μm - 1.4 μm) and H (1.5 μm - 1.8 μm) wavelength bands. Furthermore, the polarisation behaviour, the wavelength behaviour and interferometric performance has been investigated to create an accurate transfer matrix of the device.
Nulling interferometry has emerged as a promising technique for imaging exoplanets, effectively overcoming the challenges of contrast and angular resolution faced by ground-based telescopes. The Guided Light Interferometric Nulling Technology (GLINT) instrument at the Subaru telescope in Hawaii utilises this technique, where a new integrated optics beam combiner will be deployed, capable of simultaneously performing nulling interferometry and fringe tracking. Fabricated using the femtosecond laser direct write technique in boro-aluminosilicate glass, the beam combiner integrates three single-mode waveguides as inputs to form 3 interferometric baselines. The design, fabrication and laboratory characterisation of the new beam combiner will be presented. The beam combiner comprises of 3D-printed micro lenses, a chrome mask, Y-Junctions, achromatic phase shifters and tricouplers to produce for each baseline an achromatically-nulled and two phase-sensitive bright outputs. This results in a total of 12 outputs that are directed onto a CRED2 camera.
A major endeavor of this decade is the direct characterization of young giant exoplanets at high spectral resolution to determine the composition of their atmosphere and infer their formation processes and evolution. We present the implementation and first on-sky results of the HiRISE instrument at the very large telescope (VLT), which combines the exoplanet imager SPHERE with the recently upgraded high resolution spectrograph CRIRES using single-mode fibers. After introducing the global implementation, we will present the status after commissioning and after the first science observing runs. We will, in particular, focus on the performance and th lessons learned during the development, installation and validation.
Exo-NINJA will realize nearIR R≈4000 diffraction-limited narrow-field spectro-imaging for characterization of exoplanets and circumstellar disk structures. It uniquely combines mid-R spectroscopy, high throughput, and spatial resolution, in contrast to CHARIS, which does spectro-imaging, and REACH, which is single-point (no spatial resolution). Exo-NINJA’s spectro-imaging at the telescope diffraction limit will characterize exoplanet atmospheres, detect and map (spatially and spectrally) gas accretion on protoplanets, and also detect exoplanets at small angular separation (λ/D) from their host star by spectro-astrometry. Exo-NINJA will link two instruments at the Subaru Telescope using a high-throughput hexagonal multi-mode fiber bundle (hexabundle). The fiber coupling resides between the high contrast imaging system SCExAO, which combines ExAO and coronagraph, and the medium-resolution spectrograph NINJA (R=4000 at JHK bands). Exo-NINJA will provide an end-to-end throughput of 20% compared to the 1.5% obtained with REACH. Exo-NINJA is scheduled for implementation on the Subaru Telescope’s NasIR platform in 2025; we will present a concise overview of its future installation, laboratory tests such as the throughput and focal ratio degradation (FRD) performance of optical fiber imaging hexabundles, in the NIR and the trade-offs for fiber choices for the NINJA-SCExAO hexabundle fiber cable, and the expected on sky performance.
The combination on large ground-based telescopes of extreme adaptive optics (ExAO), coronagraphy and high-dispersion spectroscopy is starting to emerge as a powerful technique for the direct characterisation of giant exoplanets. High spectral resolution not only brings a major gain in terms of accessible spectral features, but it also enables to better disentangle between the stellar and planetary signals thanks to the much higher spectral content. On-going projects such as KPIC for Keck, REACH for Subaru and HiRISE for the VLT base their observing strategy on the use of a few science fibres, one of which is dedicated to sampling the PSF of the planet, while the others sample the stellar residuals in the speckle field. The main challenge in this approach is to blindly centre the science fibre on the planet’s PSF, with typically a tolerance of less than one resolution element (0.1 λ/D). Several possible centring strategies can be adopted, either based on calibration fibres retro-injecting signal to mark the position of the science fibres or based on the use of focal-plane features introduced by the ExAO system. In this proceeding, we describe different possible approaches and we compare their centring accuracy using the MITHiC high-contrast imaging testbed. For this work, MITHiC has been upgraded to reproduce a setup close to the one that will be adopted in HiRISE, the coupling system that will soon be implemented between VLT/SPHERE and VLT/CRIRES+. Our results demonstrate that reaching a specification accuracy of 0.1 λ/D is extremely challenging regardless of the chosen centring strategy. It requires a high level of accuracy at every step of the centring procedure, which can be reached with very stable instruments. We studied the contributors to the centring error in the case of MITHiC and we quantified some of the most important terms.
New generation exoplanet imagers on large ground-based telescopes are highly optimised for the detection of young giant exoplanets in the near-infrared, but they are intrinsically limited for their characterisation by the low spectral resolution of their integral field spectrographs (R < 100). High-dispersion spectroscopy at R ≫ 104 would be a powerful tool for the characterisation of these planets, but there is currently no high-resolution spectrograph with extreme adaptive optics and coronagraphy that would enable such characterisation. With project HiRISE we propose to use fiber coupling to combine the capabilities of two flagship instruments at the Very Large Telescope in Chile: the exoplanet imager SPHERE and the high-resolution spectrograph CRIRES+. The coupling will be implemented at the telescope in early 2023. We provide a general overview of the implementation of HiRISE, of its assembly, integration and testing (AIT) phase in Europe, and a brief assessment of its expected performance based on the final hardware.
The Provence Adaptive optics Pyramid Run System (PAPYRUS) is a pyramid-based Adaptive Optics (AO) system that will be installed at the Coude focus of the 1.52m telescope (T152) at the Observatoire de Haute Provence (OHP). The project is being developed by PhD students and Postdocs across France with support from staff members consolidating the existing expertise and hardware into an RD testbed. This testbed allows us to run various pyramid wavefront sensing (WFS) control algorithms on-sky and experiment on new concepts for wavefront control with additional benefit from the high number of available nights at this telescope. It will also function as a teaching tool for students during the planned AO summer school at OHP. To our knowledge, this is one of the first pedagogic pyramid-based AO systems on-sky. The key components of PAPYRUS are a 17x17 actuators Alpao deformable mirror with a Alpao RTC, a very low noise camera OCAM2k, and a 4-faces glass pyramid. PAPYRUS is designed in order to be a simple and modular system to explore wavefront control with a pyramid WFS on sky. We present an overview of PAPYRUS, a description of the opto-mechanical design and the current status of the project.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.