The CHARIS IFS for high contrast imaging at Subaru

Tyler D. Groff*, N. Jeremy Kasdin, Mary Anne Limbach, Michael Galvin, Michael A. Carr, Gillian Knapp, Timothy Brandt, Craig Loomis, Norman Jarosik, Kyle Mede, Michael W. McElwain, Douglas B. Leviton, Kevin H. Miller, Manuel A. Quijada, Olivier Guyon, Nemanja Jovanovic, Naruhisa Takato, Masahiko Hayashi

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review

37 Citations (Scopus)


The Coronagraphic High Angular Resolution Imaging Spectrograph (CHARIS) is an integral field spectrograph (IFS) being built for the Subaru telescope. CHARIS will take spectra of brown dwarfs and hot Jovian planets in the coronagraphic image provided by the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) and AO188 adaptive optics systems.1, 2 The system is designed to detect objects five orders of magnitude dimmer than their parent star down to an 80 milliarcsecond inner working angle. For characterization, CHARIS has a high-resolution prism providing an average spectral resolution of R82, R69, and R82 in J, H, and K bands respectively. The so-called discovery mode uses a second low-resolution prism with an average spectral resolution of R19 spanning 1.15-2.37 microns (J+H+K bands). This is unique compared to other high contrast IFS designs. It augments low inner working angle performance by reducing the separation at which we can rely on spectral differential imaging. The principal challenge for a high-contrast IFS is quasi-static speckles, which cause undue levels of spectral crosstalk. CHARIS has addressed this through several key design aspects that should constrain crosstalk between adjacent spectral features to be below 1%. Sitting on the Nasmyth platform, the alignment between the lenslet array, prism, and detector will be highly stable, key for the performance of the data pipeline. Nearly every component has arrived and the project is entering its final build phase. Here we review the science case, the resulting design, status of final construction, and lessons learned that are directly applicable to future exoplanet instruments.

Original languageEnglish
Title of host publicationTechniques and Instrumentation for Detection of Exoplanets VII
EditorsStuart Shaklan
Place of PublicationBellingham, Washington
Number of pages10
ISBN (Electronic)9781628417715
Publication statusPublished - 2015
Externally publishedYes
EventTechniques and Instrumentation for Detection of Exoplanets VII - San Diego, United States
Duration: 10 Aug 201513 Aug 2015

Publication series

NameProceedings of SPIE
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


OtherTechniques and Instrumentation for Detection of Exoplanets VII
Country/TerritoryUnited States
CitySan Diego


  • Coronagraphy
  • Exoplanets
  • Extreme Adaptive Optics
  • Integral Field Spectrograph
  • Lenslet


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