First science observations with the ACES echelle spectrograph

Robert O. Reynolds, Michael Lloyd-Hart

Research output: Contribution to journalConference articlepeer-review

6 Scopus citations


The use of spectrographs with telescopes having high order adaptive optics (AO) systems offers the possibility of achieving near diffraction-limited spectral resolution with ground-based telescopes, as well as important advantages for instrument design. The use of an optical fiber to couple the instrument to the telescope affords additional advantages such as flexibility in the placement of the instrument and improved homogeneity of the input illumination function. In the case of Steward Observatory's Adaptively Coupled Echelle Spectrograph (ACES), the instrument is normally coupled to the telescope with an 8μm diameter near single-mode optical fiber, although the instrument can be used at fixed focus locations without the fiber for telescopes so equipped. The use of a fiber coupler results in the phenomenon known as 'modal noise', where the transmission of multiple modes in the fiber leads to a wavelength-dependent variation in illumination that limits flat fielding precision. We have largely eliminated this effect through the use of an automated fiber stretcher device. We report here on improvements to the fiber feed optics and on interim observations made with the instrument at a conventional telescope not equipped with adaptive optics.

Original languageEnglish (US)
Pages (from-to)172-180
Number of pages9
JournalProceedings of SPIE - The International Society for Optical Engineering
Issue numberPART 1
StatePublished - 2004
EventGround-based Instrumentation for Astronomy - Glasgow, United Kingdom
Duration: Jun 21 2004Jun 25 2004


  • Adaptive optics
  • Echelle
  • Fiber optics
  • Instrumentation
  • Spectrograph

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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