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Proceedings Paper

VPH grating technology for the Thirty Meter Telescope instrumentation program
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Paper Abstract

Volume Phase Holographic Gratings (VPHG) provide unique advantages over traditional dispersive elements and are being considered for instruments on many large telescopes, including the Wide Field Optical Spectrograph (WFOS) for the Thirty Meter Telescope (TMT). In this paper we review the properties of VPHG particularly with regard to their use in large multi-object spectrographs such as WFOS. Design considerations include optimal sizes and working angles, and variations in blaze efficiencies as a function of grating and field angles. For instruments like WFOS, a gratings mosaic is a promising solution to meet the size requirements. The methodologies of mosaics and the required tolerances are evaluated. VPH gratings may also be used in echelette mode with significant advantages, although more lab tests should be carried out to explore and optimize performance. A brief status report on the VPHG development activities in the Goodman lab is included, with a plan for future development.

Paper Details

Date Published: 25 July 2008
PDF: 10 pages
Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 70184U (25 July 2008); doi: 10.1117/12.789524
Show Author Affiliations
John S. Pazder, National Research Council Canada, Herzberg Institute of Astrophysics (Canada)
J. Christopher Clemens, Univ. of North Carolina, Chapel Hill (United States)

Published in SPIE Proceedings Vol. 7018:
Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation
Eli Atad-Ettedgui; Dietrich Lemke, Editor(s)

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