Design and calibration of a closed loop tip-tilt control for a pyramid-Shack-Hartmann hybrid wave-front sensor

Madison Jean, Justin M. Knight, Charlotte Guthery, Michael Hart, Daewook Kim

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


The Hybrid Wave-front Sensor (HyWFS) has previously been developed as a combination of a Pyramid Wave-front Sensor (PyWFS) and a Shack-Hartmann Wave-front Sensor (SHWFS) to capture the desirable properties of each when operated with an unresolved guide beacon. A pyramid prism placed at a focus divides the beacon light into four beams. At a reimaged pupil, a lenslet array creates four separate spot patterns on a detector. The measured intensities may be analyzed both in the manner of a PyWFS and a SHWFS, generating two approximations of the wave front that together achieve the high sensitivity of the PyWFS and the high dynamic range of the SHWFS. Given its inherent sensitivity, calibrating the HyWFS is challenged by the effects of local vibrations and air currents in the laboratory. To overcome this problem, a prototype HyWFS has been built that features a closed loop tip-tilt control sub-system. The design includes additional pupil planes, a Fast Steering Mirror (FSM), and a tip-tilt sensor. The prototype HyWFS will be calibrated with low-order Zernike polynomials at a variety of amplitudes to confirm the sensor's sensitivity, dynamic range, and the effectiveness of the tip-tilt control loop. The effect of the tip-tilt loop will be quantified by comparing calibration qualities while the loop is active and inactive. The residual wave-front error is anticipated to decrease with active tip-tilt control in both the PyWFS mode and the SHWFS mode. With improved accuracy, the HyWFS is another step closer to on sky operation in a closed loop adaptive optics system.

Original languageEnglish (US)
Title of host publicationUnconventional Imaging and Adaptive Optics 2021
EditorsJean J. Dolne, Mark F. Spencer
ISBN (Electronic)9781510645103
StatePublished - 2021
EventUnconventional Imaging and Adaptive Optics 2021 - San Diego, United States
Duration: Aug 1 2021Aug 5 2021

Publication series

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


ConferenceUnconventional Imaging and Adaptive Optics 2021
Country/TerritoryUnited States
CitySan Diego


  • Adaptive optics
  • Atmospheric turbulence
  • Hybrid wave-front sensor
  • Pyramid wave-front sensor
  • Shack-Hartmann wave-front sensor
  • Tip-tilt control
  • Wave-front sensing

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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