A conceptual design for the Thirty Meter Telescope adaptive optics systems

Ellerbroek, Brent L.; Boyer, Corinne; Bradley, Colin; Britton, M. C.; Browne, Stephen L.; Buchroeder, R. A.; Carel, Jean-Louis; Cho, M. K.; Chun, Mark; Clare, Richard; Conan, Rodolphe; Daggert, Larry; Dekany, Richard; Elias, J. H.; Erickson, Darren; Flicker, Ralf; Gavel, Donald T.; Gilles, Luc; Hampton, Peter J.; Herriot, Glen; Hunten, Mark; Joyce, R. R.; Liang, Ming; Macintosh, Bruce; Palomo, Richard; Powell, Ian; Roberts, Scott; Ruch, Eric; Smith, Malcolm J.; Stoesz, J.; Troy, Mitchell; Tyler, Glenn A.; Véran, Jean-Pierre; Vogel, Curtis R.; Yang, Qiang

doi:10.1117/12.669422

Cited by 14 publications

(6 citation statements)

References 25 publications

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“…The top-level requirements for the DMs (which must be satisfied at the NFIRAOS operating temperature of -30C) include 8-10 µm actuator stroke, 5% hysteresis, and a mirror figure error after flattening of 20 nm RMS. As presented previously 27 , all of these requirements have been demonstrated by the subscale 9x9 prototype DM which was fabricated and tested by CILAS in 2006. More recently, a 41x41 CILAS DM has been successfully demonstrated for the ESO SPHERE AO system using the same materials and components in a very similar design 28 .…”

Section: Wavefront Correctorsmentioning

confidence: 91%

Progress toward developing the TMT adaptive optical systems and their components

et al. 2008

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Atmospheric turbulence compensation via adaptive optics (AO) will be essential for achieving most objectives of the TMT science case. The performance requirements for the initial implementation of the observatory's facility AO system include diffraction-limited performance in the near IR with 50 per cent sky coverage at the galactic pole. This capability will be achieved via an order 60x60 multi-conjugate AO system (NFIRAOS) with two deformable mirrors optically conjugate to ranges of 0 and 12 km, six high-order wavefront sensors observing laser guide stars in the mesospheric sodium layer, and up to three low-order, IR, natural guide star wavefront sensors located within each client instrument. The associated laser guide star facility (LGSF) will consist of 3 50W class, solid state, sum frequency lasers, conventional beam transport optics, and a launch telescope located behind the TMT secondary mirror. In this paper, we report on the progress made in designing, modeling, and validating these systems and their components over the last two years. This includes work on the overall layout and detailed opto-mechanical designs of NFIRAOS and the LGSF; reliable wavefront sensing methods for use with elongated and time-varying sodium laser guide stars; developing and validating a robust tip/tilt control architecture and its components; computationally efficient algorithms for very high order wavefront control; detailed AO system modeling and performance optimization incorporating all of these effects; and a range of supporting lab/field tests and component prototyping activities at TMT partners. Further details may be found in the additional papers on each of the above topics.

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Section: Wavefront Correctorsmentioning

confidence: 91%

Progress toward developing the TMT adaptive optical systems and their components

et al. 2008

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“…The details of the TMT adaptive optics architecture are explained elsewhere 13 . There is a large amount of commonality in the Gemini, VLT, ALMA, LSST, SOLIS, VISTA, and ATST software architecture, and it is possible to characterize what is called a reference architecture or domain-specific architecture for observatory software systems.…”

Section: Architecturementioning

confidence: 99%

Systems engineering for the conceptual design of the Thirty Meter Telescope

Angeli

2006

SPIE Proceedings

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A large, ground based telescope project like the Thirty Meter Telescope project faces unique systems engineering challenges stemming from the inevitably distributed, international nature of the endeavor, as well as the relative novelty of formal systems engineering in ground based astronomy. The TMT project established solid systems engineering processes in the conceptual design phase, including project lifecycle configuration management, requirements engineering, and a web based document library. The outlines of the highest level engineering documents, the Observatory Requirements and Observatory Architecture are presented. As integrated and end-to-end modeling is an organic part of systems engineering in support of performance allocation and trade studies, an important example, the analysis of wind and thermal induced local seeing, is briefly described in the paper.

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“…System performance is characterized in terms of the residual RMS wavefront error remaining after AO correction, which is an appropriate metric for the TMT natural guide star (NGS) AO and laser guide star (LGS) AO modes including multi-conjugate AO (MCAO), mid infra-red AO (MIRAO), ground-layer AO (GLAO), and multi-object AO (MOAO). 5 This analysis can be used to assist in the initial development of tolerances for the TMT primary mirror figure and alignment errors, although higher fidelity simulations will still be required to understand the higher-order impacts of primary mirror errors on certain AO modes in greater detail (For example, their effect on the image contrast achievable using an Extreme AO (ExAO) system. 6 ).…”

Section: Introductionmentioning

confidence: 99%

Spatial frequency domain model for adaptive optics compensation of segmented mirror misalignments and figure errors

Ellerbroek

2006

SPIE Proceedings

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In addition to their essential function of providing atmospheric turbulence compensation, astronomical Adaptive Optical (AO) systems also supplement the role of active optics (aO) by providing some additional correction of the wavefront aberrations introduced by mirror mounting, alignment, thermal distortion and/or fabrication errors. This feature is particularly desirable for segmented mirror telescopes such as the Thirty Meter Telescope (TMT), but wavefront discontinuities across segment boundaries are challenging to properly sense and correct. In this paper we describe a fast, analytical, frequency domain model which may be used to study and quantify the above effects, and discuss a range of sample results obtained to support the development of the top-level requirements for the TMT primary mirror. In general, AO compensation of mirror segment piston errors is not particulary useful unless the deformable mirror (DM) interactuator spacing is equivalent to no more than one-half of a mirror segment diameter (when both of these dimensions are expressed in the same pupil plane). Effective AO compensation of mirror segment tip/tilt errors, or low order segment figure errors such as astigmatism, typically requires 3-4 DM actuators per mirror segment. These results illustrate the importance of quantifying and minimizing uncorrectable telescope wavefront errors when developing performance predictions for adaptive optical systems.

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A conceptual design for the Thirty Meter Telescope adaptive optics systems

Cited by 14 publications

References 25 publications

Progress toward developing the TMT adaptive optical systems and their components

Progress toward developing the TMT adaptive optical systems and their components

Systems engineering for the conceptual design of the Thirty Meter Telescope

Spatial frequency domain model for adaptive optics compensation of segmented mirror misalignments and figure errors

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