Optical Fabrication and Metrology for the Thirty Meter Telescope Primary Mirror Segments

Cole, Glen

doi:10.1364/oft.2017.ow1b.4

Cited by 7 publications

(3 citation statements)

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“…We have applied the IAH to a segmented aperture similar to that used in the Thirty Meter Telescope (TMT; Nelson & Sanders 2008 ;Sch öck et al 2009 ;Cole 2017 ), one of the largest and most technologically advanced telescopes in the world. Scheduled for construction at Mauna Kea, Hawaii, USA, and it is planned that the telescope will MNRAS 523, 5442-5451 (2023) have its first light in the early 2030s, this ground-based astronomical observatory is a collaborative effort among astronomical communities from India, Canada, China, Japan, and the United States, who are jointly determining the scientific goals, array of instruments, and o v erall design of the TMT observ atory (Si v arani et al 2022 ).…”

Section: Tmt Aperturementioning

confidence: 99%

Interferometric apodization by homothety – I. Optimization of the device parameters

Chafi

Azhari

Azagrouze

et al. 2023

Monthly Notices of the Royal Astronomical Society

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This study is focused on the very high dynamic imaging field, specifically the direct observation of exoplanetary systems. The coronagraph is an essential technique for suppressing the star’s light, making it possible to detect an exoplanet with a very weak luminosity compared to its host star. Apodization improves the rejection of the coronagraph, thereby increasing its sensitivity. This work presents the apodization method by interferometry using homothety, with either a rectangular or circular aperture. We discuss the principle method, the proposed experimental setup, and present the obtained results by optimizing the free parameters of the system while concentrating the maximum of the light energy in the central diffraction lobe, with a concentration rate of 93.6% for the circular aperture and 91.5% for the rectangular geometry. The obtained results enabled scaling the various elements of the experiment in accordance with practical constraints. Simulation results are presented for both circular and rectangular apertures. We performed simulations on a hexagonal aperture, both with and without a central obstruction, as well as a segmented aperture similar to the one used in the Thirty Meter Telescope (TMT). This approach enables the attainment of a contrast of approximately 10−4 at small angular separations, specifically around 1.8λ/D. When integrated with a coronagraph, this technique exhibits great promise. These findings confirm that our proposed technique can effectively enhance the performance of a coronagraph.

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Section: Tmt Aperturementioning

confidence: 99%

Interferometric apodization by homothety – I. Optimization of the device parameters

Chafi

Azhari

Azagrouze

et al. 2023

Monthly Notices of the Royal Astronomical Society

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“…Furthermore, the Giant Magellan Telescope (GMT) has a 24.5 m diameter [5], the Thirty Meter Telescope (TMT) has a 30 m diameter [6], and the European Extremely Large Telescope (EELT) has a 39.3 m diameter [7]. Telescopes are being developed with significantly larger diameters, reaching tens of meters.…”

Section: Introductionmentioning

confidence: 99%

Fabrication of a 4 m SiC Aspheric Mirror Using an Optimized Strategy of Dividing an Error Map

Liu,

Li,

et al. 2024

Photonics

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This paper introduces an optimization strategy for fabricating large aspheric mirrors. We polished a large SiC aspheric mirror, 4 m in diameter, achieving a surface error of 1/40λ RMS. To the best of our knowledge, this is the first instance of such a result for a mirror of this material and size combination. Due to the various performance settings of different tools, achieving optimal polishing results with a single setting is challenging. We evaluated the performance of various tool settings and developed an optimization strategy, dividing error maps to enhance efficiency in large-aperture aspheric mirror fabrication. We established the relationship between tool size and its error control capability. The residual error map of the mirror was divided into two parts using Zernike polynomial expansion based on the frequency order of the error map. Here, we used the first 36 terms of the Zernike polynomial fit to define a low-order error map, and the residual error was used to define a high-order error map. Large tools were used to correct the low-order frequency error map, whereas small tools were used to correct the high-order frequency error map. Therefore, the original residual error map could be corrected with significantly high efficiency. By employing this strategy, we fabricated a 4 m SiC aspheric mirror in 18 months, achieving a final surface error better than 0.024λ RMS.

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“…Ground-based telescopes, including optical and near-infrared ones used for imaging and spectroscopic observations, are still among astronomy's most indispensable observing facilities. To gain a deeper and more detailed view of the universe, the diameter of the primary mirror for ground-based telescopes has dramatically increased to as large as 24.5m (e.g., Giant Magellan Telescope), 30m (e.g., Thirty Meter Telescope) and 39m (e.g., European Extremely Large Telescope) [1][2][3][4] in the last 30 years. At the same time, astronomy now also requires increasingly larger and deeper surveys of the sky, including imaging and spectroscopic ones.…”

Section: Introductionmentioning

confidence: 99%

Conceptual Design of the Optical System of the 6.5m Wide Field MUltiplexed Survey Telescope with Excellent Image Quality

Zhang

Jiang

Shectman

et al. 2022

Preprint

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Astrophysics and cosmology in the coming decades urgently need a large field-of-view (FOV), highly multiplexed spectroscopic survey telescope satisfying challenging image quality and stability requirements. The 6.5m MUltiplexed Survey Telescope (MUST) proposed by Tsinghua University will be constructed on the Saishiteng Mountain of Northwest China to improve the spectroscopic survey capability of ground-based optical telescopes. In this paper, we demonstrate the conceptual design of the optical system of MUST. MUST will adopt a 6.5m primary mirror, a 2.45m secondary mirror, and a multiple-element widefield corrector (WFC) to ensure excellent image quality with an 80% encircled energy size of image spots less than ~ 0.6 arcsec in diameter for the entire 3° FOV and the whole 50° zenith angle range. Thanks to its compact 6.5m Ritchey-Chretien system and 20000 optical fibers on its Cassegrain focus, MUST will carry out state-of-the-art wide-field spectroscopic surveys with efficiency ~ 19 times higher than the Dark Energy Spectroscopic Instrument (DESI) using a measure proposed by Ellis et al. Upon completion around 2029, MUST will be one of the world's largest and most advanced wide-field spectroscopic survey telescopes and a new essential reference for the future development of wide-field survey telescopes. It will enable significant advances in many fields in astrophysics and cosmology.

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Optical Fabrication and Metrology for the Thirty Meter Telescope Primary Mirror Segments

Cited by 7 publications

References 0 publications

Interferometric apodization by homothety – I. Optimization of the device parameters

Interferometric apodization by homothety – I. Optimization of the device parameters

Fabrication of a 4 m SiC Aspheric Mirror Using an Optimized Strategy of Dividing an Error Map

Conceptual Design of the Optical System of the 6.5m Wide Field MUltiplexed Survey Telescope with Excellent Image Quality

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