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25 July 2008 VPH grating technology for the Thirty Meter Telescope instrumentation program
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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.
© (2008) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
John S. Pazder and J. Christopher Clemens "VPH grating technology for the Thirty Meter Telescope instrumentation program", Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 70184U (25 July 2008);

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