Pupil-plane LLOWFS simulation and laboratory results from NEW-EARTH's high-contrast imaging testbed

Garima Singh*, William Thompson, Olivier Lardière, Christian Marois, Mamadou N'Diaye, Adam B. Johnson, Jean Pierre Véran, Glen Herriot, Benjamin Gerard, Qiang Fu, Wolfgang Heidrich

*Corresponding author for this work

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

5 Scopus citations


Direct imaging of exoplanets can be used to characterize exoplanets by spectroscopy of their atmospheres. Coronagraphs are required to suppress the diffraction effects by blocking the starlight, however, residual wavefront error scatters starlight in the science images, losing faint exoplanet photons in stellar noise. The performance of a coronagraphic system is thus contingent upon how efficiently the wavefront aberrations are minimized. Lyot-stop low-order wavefront sensor (LLOWFS) is a well-established sensor that senses the light rejected by the focal plane mask and corrects low-order aberrations upstream of the coronagraph. Previous versions of the LLOWFS sensed the residual starlight at the defocused focal plane. However, on the NRC's NEW-EARTH high-contrast imaging testbed, pupil-plane images of LLOWFS have been used to address both Zernike and Fourier modes. The goal of the testbed is to develop SPIDERS/Subaru which is the technology demonstrator of the CAL2 unit of the upcoming Gemini Planet Imager 2.0 (GPI 2.0). Both SPIDERS and CAL2 will address the low-order modes for stabilizing speckles, and demonstrate an active suppression of speckles using the Fast Atmospheric Self-Coherent Camera Technique (FAST) by creating a region of up to 10−7 contrast at small angles. Thus, obtaining sub-nanometric pointing stability using the LLOWFS is crucial for achieving stable contrast results on the bench and on-sky. Here, we present LLOWFS closed-loop laboratory results under simulated post-Adaptive Optics residuals of GPI 2.0 and simulations of the LLOWFS and FAST sensors for SPIDERS.

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


  • Coronagraph
  • Direct Imaging of Exoplanets
  • Extreme-Adaptive Optics
  • Low-order Wavefront Sensor

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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