A two-band approach to nλ phase error corrections with LBTI's PHASECam

E. R. Maier, Philip M Hinz, D. Defrère, S. Ertel, E. Downey

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

Abstract

PHASECam is the Large Binocular Telescope Interferometer's (LBTI) phase sensor, a near-infrared camera which is used to measure tip/tilt and phase variations between the two AO-corrected apertures of the Large Binocular Telescope (LBT). Tip/tilt and phase sensing are currently performed in the H (1.65 μm) and K (2.2 μm) bands at 1 kHz, and the K band phase telemetry is used to send tip/tilt and Optical Path Difference (OPD) corrections to the system. However, phase variations outside the range [-Π, Π] are not sensed, and thus are not fully corrected during closed-loop operation. PHASECam's phase unwrapping algorithm, which attempts to mitigate this issue, still occasionally fails in the case of fast, large phase variations. This can cause a fringe jump, in which case the unwrapped phase will be incorrect by a wavelength or more. This can currently be manually corrected by the observer, but this is inefficient. A more reliable and automated solution is desired, especially as the LBTI begins to commission further modes which require robust, active phase control, including controlled multi-axial (Fizeau) interferometry and dual-aperture non-redundant aperture masking interferometry. We present a multi-wavelength method of fringe jump capture and correction which involves direct comparison between the K band and currently unused H band phase telemetry.

Original languageEnglish (US)
Title of host publicationOptical and Infrared Interferometry and Imaging VI
EditorsPeter G. Tuthill, Michelle J. Creech-Eakman, Antoine Merand
PublisherSPIE
Volume10701
ISBN (Print)9781510619555
DOIs
StatePublished - Jan 1 2018
Event2018 Optical and Infrared Interferometry and Imaging VI - Austin, United States
Duration: Jun 11 2018Jun 15 2018

Other

Other2018 Optical and Infrared Interferometry and Imaging VI
CountryUnited States
CityAustin
Period6/11/186/15/18

Fingerprint

Phase Error
Binoculars
phase error
Error correction
Error Correction
Telescopes
telemetry
apertures
telescopes
Telemetering
extremely high frequencies
Interferometry
Interferometers
interferometry
interferometers
Tip-tilt
Wavelength
Phase control
phase control
masking

Keywords

  • Fizeau imaging
  • Fringe tracking
  • Infrared interferometry
  • LBT
  • Nulling interferometry

ASJC Scopus subject areas

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

Cite this

Maier, E. R., Hinz, P. M., Defrère, D., Ertel, S., & Downey, E. (2018). A two-band approach to nλ phase error corrections with LBTI's PHASECam. In P. G. Tuthill, M. J. Creech-Eakman, & A. Merand (Eds.), Optical and Infrared Interferometry and Imaging VI (Vol. 10701). [107011M] SPIE. https://doi.org/10.1117/12.2313627

A two-band approach to nλ phase error corrections with LBTI's PHASECam. / Maier, E. R.; Hinz, Philip M; Defrère, D.; Ertel, S.; Downey, E.

Optical and Infrared Interferometry and Imaging VI. ed. / Peter G. Tuthill; Michelle J. Creech-Eakman; Antoine Merand. Vol. 10701 SPIE, 2018. 107011M.

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

Maier, ER, Hinz, PM, Defrère, D, Ertel, S & Downey, E 2018, A two-band approach to nλ phase error corrections with LBTI's PHASECam. in PG Tuthill, MJ Creech-Eakman & A Merand (eds), Optical and Infrared Interferometry and Imaging VI. vol. 10701, 107011M, SPIE, 2018 Optical and Infrared Interferometry and Imaging VI, Austin, United States, 6/11/18. https://doi.org/10.1117/12.2313627
Maier ER, Hinz PM, Defrère D, Ertel S, Downey E. A two-band approach to nλ phase error corrections with LBTI's PHASECam. In Tuthill PG, Creech-Eakman MJ, Merand A, editors, Optical and Infrared Interferometry and Imaging VI. Vol. 10701. SPIE. 2018. 107011M https://doi.org/10.1117/12.2313627
Maier, E. R. ; Hinz, Philip M ; Defrère, D. ; Ertel, S. ; Downey, E. / A two-band approach to nλ phase error corrections with LBTI's PHASECam. Optical and Infrared Interferometry and Imaging VI. editor / Peter G. Tuthill ; Michelle J. Creech-Eakman ; Antoine Merand. Vol. 10701 SPIE, 2018.
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