RISTRETTO: coronagraph and AO designs enabling High Dispersion Coronagraphy at 2 λ/D

N. Blind, B. Chazelas, J. Kühn, E. Hocini, C. Lovis, M. Beaulieu, T. Fusco, L. Genolet, O. Guyon, J. Hagelberg, I. Hughes, P. Martinez, J. F. Sauvage, R. Schnell, M. Sordet, A. Spang

Research output: Chapter in Book/Report/Conference proceedingConference contribution

2 Scopus citations


RISTRETTO is the evolution of the original idea of coupling the VLT instruments SPHERE and ESPRESSO,1 aiming at High Dispersion Coronagraphy. RISTRETTO is a visitor instrument that should enable the characterization of the atmospheres of nearby exoplanets in reflected light, by using the technique of high-contrast, high-resolution spectroscopy. Its goal is to observe Prox Cen b and other planets placed at about 35mas from their star, i.e. 2λ/D at λ=750nm. The instrument is composed of an extreme adaptive optics, a coronagraphic Integral Field Unit, and a diffraction-limited spectrograph (R=140.000, λ =620-840 nm). We present the status of our studies regarding the coronagraphic IFU and the XAO system. The first in particular is based on a modified version of the PIAA apodizer, allowing nulling on the first diffraction ring. Our proposed design has the potential to reach ≥ 50% coupling and ≤ 10−4 contrast at 2λ/D in median seeing conditions.

Original languageEnglish (US)
Title of host publicationAdaptive Optics Systems VIII
EditorsLaura Schreiber, Dirk Schmidt, Elise Vernet
ISBN (Electronic)9781510653511
StatePublished - 2022
EventAdaptive Optics Systems VIII 2022 - Montreal, Canada
Duration: Jul 17 2022Jul 22 2022

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceAdaptive Optics Systems VIII 2022


  • HDC
  • nulling
  • PIAA
  • XAO

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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