Active thermal figure control concept for the TOPS II primary mirror

J Roger P Angel, Kang Tae, Brian Cuerden, Olivier Guyon, Phil Stahl

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

2 Citations (Scopus)

Abstract

TOPS (Telescope to Observe Planetary Systems) is the first coronagraphic telescope concept designed specifically to take advantage of Guyon's method of Phase Induced Amplitude Apodization PIAA).1 The TOPS primary mirror may incorporates active figure control to help achieve the desired wavefront control to approximately 1 ÅRMS accurate across the spectral bandwidth. Direct correction of the primary figure avoids the need for a separate small deformable mirror. Because of Fresnel propagation, correction at a separate surface can introduce serious chromatic errors unless it is precisely conjugated to the primary. Active primary control also reduces complexity and mass and increases system throughput, and will likely enable a full system test to the 10-10 level in the 1 g environment before launch. We plan to use thermal actuators with no mechanical disturbance, using radiative heating or cooling fingers distributed inside the cells of a honeycomb mirror. The glass would have very small but finite coefficient of expansion of ∼ 5×10 -8/C. Low order modes would be controlled by front-to-back gradients and high order modes by local rib expansion and contraction. Finite element models indicate that for a mirror with n cells up to n Zeraike modes can be corrected to better than 90% fidelity, with still higher accuracy for the lower modes. An initial demonstration has been made with a borosilicate honeycomb mirror. Interferometric measurements show a single cell influence function with 300 nm stroke and ∼5 minute time constant.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
Volume6693
DOIs
StatePublished - 2007
EventTechniques and Instrumentation for Detection of Exoplanets III - San Diego, CA, United States
Duration: Aug 28 2007Aug 30 2007

Other

OtherTechniques and Instrumentation for Detection of Exoplanets III
CountryUnited States
CitySan Diego, CA
Period8/28/078/30/07

Fingerprint

planetary systems
Telescopes
honeycomb mirrors
Mirrors
telescopes
mirrors
cells
apodization
expansion
deformable mirrors
strokes
time constant
contraction
Wavefronts
disturbances
actuators
bandwidth
cooling
Demonstrations
Actuators

Keywords

  • Coronagraph
  • Deformable mirror
  • Exoplanets
  • Space telescope

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Angel, J. R. P., Tae, K., Cuerden, B., Guyon, O., & Stahl, P. (2007). Active thermal figure control concept for the TOPS II primary mirror. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 6693). [669313] https://doi.org/10.1117/12.734930

Active thermal figure control concept for the TOPS II primary mirror. / Angel, J Roger P; Tae, Kang; Cuerden, Brian; Guyon, Olivier; Stahl, Phil.

Proceedings of SPIE - The International Society for Optical Engineering. Vol. 6693 2007. 669313.

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

Angel, JRP, Tae, K, Cuerden, B, Guyon, O & Stahl, P 2007, Active thermal figure control concept for the TOPS II primary mirror. in Proceedings of SPIE - The International Society for Optical Engineering. vol. 6693, 669313, Techniques and Instrumentation for Detection of Exoplanets III, San Diego, CA, United States, 8/28/07. https://doi.org/10.1117/12.734930
Angel JRP, Tae K, Cuerden B, Guyon O, Stahl P. Active thermal figure control concept for the TOPS II primary mirror. In Proceedings of SPIE - The International Society for Optical Engineering. Vol. 6693. 2007. 669313 https://doi.org/10.1117/12.734930
Angel, J Roger P ; Tae, Kang ; Cuerden, Brian ; Guyon, Olivier ; Stahl, Phil. / Active thermal figure control concept for the TOPS II primary mirror. Proceedings of SPIE - The International Society for Optical Engineering. Vol. 6693 2007.
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