Experimental study of a low-order wavefront sensor for the high-contrast coronagraphic imager EXCEDE

Julien Lozi, Ruslan Belikov, Glenn Schneider, Olivier Guyon, Eugene Pluzhnik, Sandrine J. Thomas, Frantz Martinache

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

6 Scopus citations


The mission EXCEDE (EXoplanetary Circumstellar Environments and Disk Explorer), selected by NASA for technology development, is designed to study the formation, evolution and architectures of exoplanetary systems and characterize circumstellar environments into stellar habitable zones. It is composed of a 0.7 m telescope equipped with a Phase-Induced Amplitude Apodization Coronagraph (PIAA-C) and a 2000-element MEMS deformable mirror, capable of raw contrasts of 10-6 at 1.2 λ/D and 10-7 above 2 λ/D. One of the key challenges to achieve those contrasts is to remove low-order aberrations, using a Low-Order WaveFront Sensor (LOWFS). An experiment simulating the starlight suppression system is currently developed at NASA Ames Research Center, and includes a LOWFS controlling tip/tilt modes in real time at 500 Hz. The LOWFS allowed us to reduce the tip/tilt disturbances to 10 -3 λ/D rms, enhancing the previous contrast by a decade, to 8 × 10-7 between 1.2 and 2 λ/D. A Linear Quadratic Gaussian (LQG) controller is currently implemented to improve even more that result by reducing residual vibrations. This testbed shows that a good knowledge of the low-order disturbances is a key asset for high contrast imaging, whether for real-time control or for post processing.

Original languageEnglish (US)
Title of host publicationTechniques and Instrumentation for Detection of Exoplanets VI
StatePublished - 2013
EventTechniques and Instrumentation for Detection of Exoplanets VI - San Diego, CA, United States
Duration: Aug 26 2013Aug 29 2013

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 VI
Country/TerritoryUnited States
CitySan Diego, CA


  • Control
  • Coronagraph
  • High-contrast imaging
  • Linear quadratic Gaussian controller
  • Low-order wavefront sensor
  • PIAA

ASJC Scopus subject areas

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


Dive into the research topics of 'Experimental study of a low-order wavefront sensor for the high-contrast coronagraphic imager EXCEDE'. Together they form a unique fingerprint.

Cite this