&lt;title&gt;Gemini telescope structure design&lt;/title&gt;

Raybould, Keith; Gillett, Paul; Hatton, P. D.; Pentland, Gordon; Sheehan, Mike; Warner, Mark

doi:10.1117/12.176205

Cited by 3 publications

(3 citation statements)

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“…In addition, other telescopes such as the W M Keck, Very Large Telescope, Subaru, and Gemini have primary and secondary mirror sizes * Authors to whom any correspondence should be addressed. of 8 and 10 m and 1 and 1.4 m, respectively [1][2][3][4][5]. However, as the mirror size increases, it becomes more challenging to fabricate and test the diffraction-limited optical performance of the mirror.…”

Section: Introductionmentioning

confidence: 99%

Astigmatism correction of convex aspheres using the subaperture stitching hindle test

Kim¹,

Song²,

Kihm³

et al. 2022

Meas. Sci. Technol.

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We propose an astigmatism correction method for the subaperture stitching Hindle test to measure hyperbolic convex aspheres. Astigmatic wavefront errors arise from misaligned Hindle setups, mechanical runout errors of the rotational motion for stitching, and the surface error of the target itself. Because these errors are combined, they cannot be separated in the conventional subaperture stitching Hindle tests. We exploited the rotational periodicity of each error to distinguish the surface figure error from other astigmatic error sources and rectified the Hindle test results with a third-order astigmatism. Using the subaperture stitching Hindle test, we averaged two sets of measurement data with a 180° rotational phase difference between them to calculate the astigmatic surface error. The proposed method was verified experimentally by comparing it with the results from a commercial stitching interferometer from QED Technologies; only subnanometer differences in the root-mean-square values were obtained. Therefore, the proposed method calibrated the system errors from the test surface wedge and the rotational decenter easily, thereby reducing the mechanical costs and alignment efforts and making it more accessible than a sophisticated mechanism.

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Section: Introductionmentioning

confidence: 99%

Astigmatism correction of convex aspheres using the subaperture stitching hindle test

Kim¹,

Song²,

Kihm³

et al. 2022

Meas. Sci. Technol.

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“…Stress and buckling in the tube members limit the tube-wall thickness ͑Section 3͒, so designs with h close to zero may not be practical; they are in any case of limited interest because the tube stiffness is low, so wind-induced decenter of the secondary is high. If h is small, the bottom tube will be stiff enough to support the elevation axis, as in the Gemini design, 5 ; otherwise a stiff ring must be included between the top and bottom tubes, as in the Keck telescopes. 1 Adding a ring will increase the mass of the telescope and reduce its fundamental frequency.…”

Section: Blockage and Decentermentioning

confidence: 99%

“…In most telescopes ͑e.g., Keck, 1 the Very Large Telescope, 2 Subaru, 3 and Magellan 4 ͒, the elevation axis, which provides access to the Nasmyth foci, is in front of the primary. ͑An exception is Gemini, 5 which cannot support a Nasmyth focus because the elevation axis intersects the primary.͒ Proposed designs for the next generation of large optical telescopes have abandoned the tube, or at least its upper section, in favor of a tripod or quadrupod secondary support to reduce the effects of wind buffeting ͑see Section 4 below͒. Most of the designs ͓e.g., the Giant Segmented Mirror Telescope 6 and Euro50 ͑Ref.…”

Section: Introductionmentioning

confidence: 99%

Location of the elevation axis in a large optical telescope

Padin

2004

Appl. Opt.

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Proposed designs for the next generation of large optical telescopes favor a tripod or quadrupod secondary support, and a primary supported from the back, but it is not yet clear whether the elevation axis should be in front of the primary or behind it. A study is described of the effect of elevation-axis location on key performance parameters ͑fundamental frequency, blockage, and wind-induced secondary decenter͒ for a 30-m Cassegrain telescope with a mount configuration that is typical of the new designs. For a fast ͑e.g., f͞1͒ primary, the best location for the elevation axis is behind the primary. The penalty for moving the elevation axis in front of the primary is roughly a 40% decrease in fundamental frequency and a corresponding reduction in the control bandwidth for pointing and optical alignment.

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Optical Instrument Structural Design

2005

Optical Science and Engineering

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<title>Gemini telescope structure design</title>

Cited by 3 publications

References 0 publications

Astigmatism correction of convex aspheres using the subaperture stitching hindle test

Astigmatism correction of convex aspheres using the subaperture stitching hindle test

Location of the elevation axis in a large optical telescope

Optical Instrument Structural Design

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