Cryogenic beam-combiner for very low background, 2-20 micron interferometry on the 22.8 m Large Binocular Telescope

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

6 Citations (Scopus)

Abstract

The 22.8 m Large Binocular Telescope Interferometer will be a uniquely powerful tool for imaging and nulling interferometry at thermal infrared wavelengths (2-20 μm) because of the LBT's unusual combination of low emissivity, high spatial resolution, broad (u,v)-plane coverage, and high photometric sensitivity. The Gregorian adaptive secondary mirrors permit beam combination after only three warm reflections. They also control the relative pathlength, wavefront tip/tilt, and focus of the two telescope beams, thus greatly simplifying the complexity of the beam-combiner. The resulting four-mirror beam-combiner reimages the original focal plane and also images the telescope pupil onto a cold stop to limit thermal background. At first-light in 2004, an all-reflective, cooled beam-combiner can provide a 2 arcmin diameter field for Fizeau-style imaging as well as the low thermal background and achromaticity required for nulling interferometry. In designing the optics of such a beam-combiner, we can maximize the field of view at the combined focus by balancing the competing effects of differential phase, tilt, distortion, focus, and pupil matching. To achieve a `peak Strehl' of 0.9 at a wavelength of 4.8 μm across a 1.0 arcmin field radius, strong constraints are placed on differential image overlap (approximately 0.03 arcsec), single beam distortion (0.1%), and pupil matching (0.1%). This cryogenic beam-combiner can feed a variety of interchangeable cameras and spectrographs. Tip/tilt and pathlength (phase) sensors near the final focus within each science instrument will control the adaptive secondaries to maintain precise alignment and provide the highest possible Strehl ratio.

Original languageEnglish (US)
Title of host publicationProceedings of SPIE - The International Society for Optical Engineering
PublisherSociety of Photo-Optical Instrumentation Engineers
Volume4006
StatePublished - 2000
EventInterferometry in Optical Astronomy - Munich, Ger
Duration: Mar 27 2000Mar 29 2000

Other

OtherInterferometry in Optical Astronomy
CityMunich, Ger
Period3/27/003/29/00

Fingerprint

Binoculars
Interferometry
Telescopes
Cryogenics
cryogenics
interferometry
telescopes
pupils
Imaging techniques
Wavelength
Spectrographs
Wavefronts
Interferometers
mirrors
Optics
Mirrors
Cameras
Infrared radiation
emissivity
wavelengths

ASJC Scopus subject areas

  • Electrical and Electronic Engineering
  • Condensed Matter Physics

Cite this

Mccarthy, D. W., Sabatke, E., Sarlot, R., Hinz, P. M., & Burge, J. H. (2000). Cryogenic beam-combiner for very low background, 2-20 micron interferometry on the 22.8 m Large Binocular Telescope. In Proceedings of SPIE - The International Society for Optical Engineering (Vol. 4006). Society of Photo-Optical Instrumentation Engineers.

Cryogenic beam-combiner for very low background, 2-20 micron interferometry on the 22.8 m Large Binocular Telescope. / Mccarthy, Donald W; Sabatke, E.; Sarlot, R.; Hinz, Philip M; Burge, James H.

Proceedings of SPIE - The International Society for Optical Engineering. Vol. 4006 Society of Photo-Optical Instrumentation Engineers, 2000.

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

Mccarthy, DW, Sabatke, E, Sarlot, R, Hinz, PM & Burge, JH 2000, Cryogenic beam-combiner for very low background, 2-20 micron interferometry on the 22.8 m Large Binocular Telescope. in Proceedings of SPIE - The International Society for Optical Engineering. vol. 4006, Society of Photo-Optical Instrumentation Engineers, Interferometry in Optical Astronomy, Munich, Ger, 3/27/00.
Mccarthy DW, Sabatke E, Sarlot R, Hinz PM, Burge JH. Cryogenic beam-combiner for very low background, 2-20 micron interferometry on the 22.8 m Large Binocular Telescope. In Proceedings of SPIE - The International Society for Optical Engineering. Vol. 4006. Society of Photo-Optical Instrumentation Engineers. 2000
Mccarthy, Donald W ; Sabatke, E. ; Sarlot, R. ; Hinz, Philip M ; Burge, James H. / Cryogenic beam-combiner for very low background, 2-20 micron interferometry on the 22.8 m Large Binocular Telescope. Proceedings of SPIE - The International Society for Optical Engineering. Vol. 4006 Society of Photo-Optical Instrumentation Engineers, 2000.
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