Identification of the focal plane wavefront control system using E-M algorithm

He Sun, N. Jeremy Kasdin, Robert Vanderbei

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

4 Scopus citations


In a typical focal plane wavefront control (FPWC) system, such as the adaptive optics system of NASA's WFIRST mission, the efficient controllers and estimators in use are usually model-based. As a result, the modeling accuracy of the system influences the ultimate performance of the control and estimation. Currently, a linear state space model is used and calculated based on lab measurements using Fourier optics. Although the physical model is clearly defined, it is usually biased due to incorrect distance measurements, imperfect diagnoses of the optical aberrations, and our lack of knowledge of the deformable mirrors (actuator gains and influence functions). In this paper, we present a new approach for measuring/estimating the linear state space model of a FPWC system using the expectation-maximization (E-M) algorithm. Simulation and lab results in the Princeton's High Contrast Imaging Lab (HCIL) show that the E-M algorithm can well handle both the amplitude and phase errors and accurately recover the system. Using the recovered state space model, the controller creates dark holes with faster speed. The final accuracy of the model depends on the amount of data used for learning.

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

All Science Journal Classification (ASJC) codes

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


  • E-M algorithm
  • Exoplanet direct imaging
  • coronagraph
  • statistical learning
  • system identification
  • wavefront correction


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