Design, fabrication, and testing of stellar coronagraphs for exoplanet imaging

Justin M. Knight, John Brewer, Ryan Hamilton, Karen Ward, Tom D. Milster, Olivier Guyon

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

5 Scopus citations


Complex-mask coronagraphs destructively interfere unwanted starlight with itself to enable direct imaging of exoplanets. This is accomplished using a focal plane mask (FPM); a FPM can be a simple occulter mask, or in the case of a complex-mask, is a multi-zoned device designed to phase-shift starlight over multiple wavelengths to create a deep achromatic null in the stellar point spread function. Creating these masks requires microfabrication techniques, yet many such methods remain largely unexplored in this context. We explore methods of fabrication of complex FPMs for a Phased-Induced Amplitude Apodization Complex-Mask Coronagraph (PIAACMC). Previous FPM fabrication efforts for PIAACMC have concentrated on mask manufacturability while modeling science yield, as well as assessing broadband wavelength operation. Moreover current fabrication efforts are concentrated on assessing coronagraph performance given a single approach. We present FPMs fabricated using several process paths, including deep reactive ion etching and focused ion beam etching using a silicon substrate. The characteristic size of the mask features is 5μm with depths ranging over 1μm. The masks are characterized for manufacturing quality using an optical interferometer and a scanning electron microscope. Initial testing is performed at the Subaru Extreme Adaptive Optics testbed, providing a baseline for future experiments to determine and improve coronagraph performance within fabrication tolerances.

Original languageEnglish (US)
Title of host publicationTechniques and Instrumentation for Detection of Exoplanets VIII
EditorsStuart Shaklan
ISBN (Electronic)9781510612570
StatePublished - 2017
EventTechniques and Instrumentation for Detection of Exoplanets VIII 2017 - San Diego, United States
Duration: Aug 8 2017Aug 10 2017

Publication series

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


OtherTechniques and Instrumentation for Detection of Exoplanets VIII 2017
Country/TerritoryUnited States
CitySan Diego


  • complex FPM
  • exoplanet imaging
  • focal plane mask
  • microfabrication
  • stellar coronagraph

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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