Design and analysis of an active optics system for a 4-m telescope mirror combining hydraulic and pneumatic supports

Lousberg, Grégory; Moreau, Vincent; Schumacher, Jean-Marc; Piérard, Maxime; Somja, Aude; Gloesener, P.; Flebus, Carlo

doi:10.1117/12.2191272

Cited by 2 publications

(2 citation statements)

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“…There are also systems that utilize an active lateral support system. In the 4.1 m Visible and Infrared Survey Telescope for Astronomy (VISTA) and the 4.2 m Daniel K. Inouye Solar Telescope, formerly known as Advanced Technology Solar Telescope, the lateral support consists of 24 pneumatic cylinders 16 , 17 . The 4.3 m Discovery Channel Telescope (DCT) and the 4.0 m Eastern Anatolia Observatory (DAG) also use double-acting pneumatic cylinders based on Schwesinger design with 36 and 24 supports, respectively 18 , 19 .…”

Section: Introductionmentioning

confidence: 99%

Active lateral support system for a thin 1-meter meniscus mirror with virtual fixed points

Schwaer,

Sinn,

Schroeer

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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.This publication presents an active lateral support system for the thin 1-m meniscus mirror of a Ritchey-Chrétien telescope system. The goal is to keep the mirror at its position under varying external influences, such as gravity and temperature, therefore maintaining the alignment and optical image quality. To achieve this, the lateral support consists of eight actuators, based on stepper motors with gearboxes, with local force measurement and three laser triangulation sensors to measure the mirror’s lateral position. A cascaded control structure with local force feedback in the inner loop and position feedback in the outer loop is proposed. In the outer loop, three single-input single-output PI-controllers are implemented to maintain mirror position in the three lateral degrees of freedom. The developed system is able to position the mirror with root mean square errors of 0.27 and 0.18 μm in translational directions and 5.1 μrad in the rotational direction over the operational altitude range with a slewing speed of 0.2 deg / s.

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Section: Introductionmentioning

confidence: 99%

Active lateral support system for a thin 1-meter meniscus mirror with virtual fixed points

Schwaer,

Sinn,

Schroeer

et al. 2023

J. Astron. Telesc. Instrum. Syst.

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“…An advanced laser system demands high-quality microlens arrays to enhance the laser intensity [11][12][13][14]. The development of space telescopes calls for ultra-precision, large-scale glass lens to explore the universe [15][16][17][18]. Electronic devices in the consumer industry are also examples of application of precision lenses, such as the aspherical lenses for smart mobile phones and large-scale liquid crystal display panels [1,[19][20][21].…”

Section: Introductionmentioning

confidence: 99%

Precision glass molding: Toward an optimal fabrication of optical lenses

Zhang

Liu

2017

Front. Mech. Eng.

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It is costly and time consuming to use machining processes, such as grinding, polishing and lapping, to produce optical glass lenses with complex features. Precision glass molding (PGM) has thus been developed to realize an efficient manufacture of such optical components in a single step. However, PGM faces various technical challenges. For example, a PGM process must be carried out within the super-cooled region of optical glass above its glass transition temperature, in which the material has an unstable non-equilibrium structure. Within a narrow window of allowable temperature variation, the glass viscosity can change from 10 5 to 10 12 Pa$s due to the kinetic fragility of the super-cooled liquid. This makes a PGM process sensitive to its molding temperature. In addition, because of the structural relaxation in this temperature window, the atomic structure that governs the material properties is strongly dependent on time and thermal history. Such complexity often leads to residual stresses and shape distortion in a lens molded, causing unexpected changes in density and refractive index. This review will discuss some of the central issues in PGM processes and provide a method based on a manufacturing chain consideration from mold material selection, property and deformation characterization of optical glass to process optimization. The realization of such optimization is a necessary step for the Industry 4.0 of PGM.

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Design and analysis of an active optics system for a 4-m telescope mirror combining hydraulic and pneumatic supports

Cited by 2 publications

References 0 publications

Active lateral support system for a thin 1-meter meniscus mirror with virtual fixed points

Active lateral support system for a thin 1-meter meniscus mirror with virtual fixed points

Precision glass molding: Toward an optimal fabrication of optical lenses

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