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Context. The Coronagraphic Instrument (CGI) on the Roman Space Telescope aims for unprecedented contrast for direct imaging of exoplanets, serving as a critical tech demo for future missions like the Habitable Worlds Observatory. This…

Instrumentation and Methods for Astrophysics · Physics 2025-06-11 Iva Laginja , Pierre Baudoz , Johan Mazoyer , Axel Potier , Raphaël Galicher , Faouzi Boussaha

The RISTRETTO instrument, a proposed visible high-contrast, high-resolution spectrograph for the VLT, has the primary science goal of detecting reflected light from nearby exoplanets and characterizing their atmospheres. Specifically, it…

Instrumentation and Methods for Astrophysics · Physics 2024-09-09 Muskan Shinde , Nicolas Blind , Christophe Lovis

Wavefront sensors (WFS) are now core components in the fields of metrology of optical systems, biomedical optics and adaptive optics systems for astronomy. Nowadays, the most popular WFS is the Shack-Hartmann, which is fully static but…

Optics · Physics 2025-07-21 Francois Hénault , Yan Feng , Alain Spang , Laura Schreiber

Uncorrected wavefront errors create speckle noise in high-contrast observations at small inner-working angles. These speckles can be sensed and controlled by using coronagraph integrated wavefront sensors. Here, we will present how the…

Instrumentation and Methods for Astrophysics · Physics 2023-10-18 Sebastiaan Y. Haffert , Jared R. Males , Olivier Guyon

The Optimal Optical Coronagraph (OOC) Workshop held at the Lorentz Center in September 2017 in Leiden, the Netherlands, gathered a diverse group of 25 researchers working on exoplanet instrumentation to stimulate the emergence and sharing…

We propose a new approach for high-contrast imaging at the diffraction limit using segmented telescopes in a modest observation bandwidth. This concept, named "spectroscopic fourth-order coronagraphy", is based on a fourth-order coronagraph…

Instrumentation and Methods for Astrophysics · Physics 2021-03-17 Taro Matsuo , Satoshi Itoh , Yuji Ikeda

We extend our previous demonstration of the first on-sky primary mirror segment closed-loop control on Keck using a vector-Zernike wavefront sensor (vZWFS), which improved the Strehl ratio on the NIRC2 science camera by up to 10 percentage…

HWO aims to directly image objects orbiting Sun-like stars, using a 6-m telescope capable of high-contrast imaging ($10^{-10}$) and spectroscopy to search for biosignatures in planets located in the habitable zone. Recent laboratory…

The 2020 Decadal Survey on Astronomy and Astrophysics tasked future space observatories with the goal of detecting and characterizing a large sample of Earth-like exoplanets. To achieve this, these observatories will require coronagraphs…

Direct imaging is the primary technique currently used to detect young and warm exoplanets and understand their formation scenarios. The extreme flux ratio between an exoplanet and its host star requires the use of coronagraphs to attenuate…

Instrumentation and Methods for Astrophysics · Physics 2023-06-01 Axel Potier , Zahed Wahhaj , Raphael Galicher , Johan Mazoyer , Pierre Baudoz , Gael Chauvin , Garreth Ruane

In an effort to transcend the limitations of differential imaging of exoplanets in the era of extremely large telescopes (ELTs), the first paper in this series established a rigorous, fully polarimetric framework for determining the science…

Instrumentation and Methods for Astrophysics · Physics 2016-02-18 Richard A. Frazin

In the last two decades many people have been searching for the optimal wavefront sensor as it can boost the performance of high-contrast imagining by orders of magnitude on the ELTs. According classical information theory, the optimal…

Instrumentation and Methods for Astrophysics · Physics 2023-10-18 Sebastiaan Y. Haffert , Jared R. Males , Olivier Guyon

In ground-based astronomy, Adaptive Optics (AO) is a pivotal technique, engineered to correct wavefront phase distortions and thereby enhance the quality of the observed images. Integral to an AO system is the wavefront sensor (WFS), which…

Instrumentation and Methods for Astrophysics · Physics 2026-05-07 Yutong Wu , Roland Wagner , Ronny Ramlau , Raymond H. Chan

In direct imaging of exoplanets from space, achieving the required dynamic range (i.e., planet-to-star contrast in brightness) currently relies on coronagraphic technology combined with active control of one or more deformable mirrors (DMs)…

Instrumentation and Methods for Astrophysics · Physics 2016-08-18 Richard A. Frazin

High contrast imaging and spectroscopy provide unique constraints for exoplanet formation models as well as for planetary atmosphere models. But this can be challenging because of the planet-to-star small angular separation and high flux…

Instrumentation and Methods for Astrophysics · Physics 2016-04-06 J. -R. Delorme , R. Galicher , P. Baudoz , G. Rousset , J. Mazoyer , O. Dupuis

High-contrast imaging systems using active control with adaptive optics (AO) are often limited by non-common path (NCP) aberrations that are seen only at the final science image. AO systems employing focal-plane wavefront sensors (FP-WFSs)…

Instrumentation and Methods for Astrophysics · Physics 2026-01-22 Aditya R. Sengupta , Lisa A. Poyneer , Benjamin L. Gerard , Rebecca Jensen-Clem , Aaron J. Lemmer

Stellar coronagraph performance is highly sensitive to optical aberrations. In order to effectively suppress starlight for exoplanet imaging applications, low-order wavefront aberrations entering a coronagraph such as tip-tilt, defocus and…

Instrumentation and Methods for Astrophysics · Physics 2015-06-17 Hari Subedi , Neil T. Zimmerman , N. Jeremy Kasdin , Kathleen Cavanagh , A J Eldorado Riggs

Direct exoplanet imaging via coronagraphy requires maintenance of high contrast in a dark hole for lengthy integration periods. Wavefront errors that change slowly over that time accumulate and cause systematic errors in the star's Point…

Instrumentation and Methods for Astrophysics · Physics 2019-03-08 Leonid Pogorelyuk , N. Jeremy Kasdin

Linking a coronagraph instrument to a spectrograph via a single mode optical fiber is a pathway towards detailed characterization of exoplanet atmospheres with current and future ground- and space-based telescopes. However, given the…

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