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30 September 2004 First science observations with the ACES echelle spectrograph
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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 8 micron 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.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Robert O. Reynolds and Michael Lloyd-Hart "First science observations with the ACES echelle spectrograph", Proc. SPIE 5492, Ground-based Instrumentation for Astronomy, (30 September 2004);

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