Technological features of the fabrication of the primary mirrors of telescopes

Semenov, A. P.; Abdulkadyrov, Magomed A.; Belousov, Sergei; Patrikeev, Alexey P.; Patrikeev, Vladimir E.; Sharov, Yury A.

doi:10.1364/jot.80.000207

Cited by 3 publications

(4 citation statements)

References 8 publications

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“…Since any local region of symmetry aspheric surface is symmetric about the meridian of the aspheric surface. Therefore, the local region is symmetric about the XZ plane, as shown in Figure 1, and in equation (2), b ¼ 0.…”

Section: Calculation Methodsmentioning

confidence: 98%

“…Therefore, it plays an important role in the projects such as high power laser engineering, large astronomical telescope project, and extreme ultraviolet lithography engineering. [1][2][3][4][5] In order to meet the requirements of high precision and mass production of aspheric element, a batch manufacturing process flow for large aspheric has been proposed, which includes ''ultra precision grinding and deterministic polishing''. Indeed, the precision grinding is utilized for shaping formation of the aspheric element firstly.…”

Section: Introductionmentioning

confidence: 99%

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Distortion of removal function based on the local asphericity of aspheric surface and the viscoelasticity of polishing tool in computer-controlled optical surfacing

Chen

Zhong

Wang

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part C:

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In the process of large aspheric optical surfaces fabrication, the distortion of the removal function is a big problem that affects the producing efficiency and accuracy, due to the misfit between the tool and the aspheric surface in the contact region. Consequently, this paper aims to find out the influence factors and the distortion rule of aspheric removal function in the computer-controlled optical surfacing. Firstly, based on the analysis of the sub-aperture polishing technology for the large aspheric optical surfaces, the local asphericity of aspheric surface and the viscoelasticity of polishing tool are supposed to be the main sources. After that, a method to calculate the local asphericity considering the misfit between the tool and the aspheric surface is proposed based on the least square method, and the viscoelasticity of the polishing tool is obtained through viscoelastic experiment. Subsequently, combining the results of the local asphericity of aspheric surface and the viscoelasticity of polishing tool, the prediction of the distortion rule of aspheric removal function is presented. Finally, the comparative experiment is carried out, and the removal function on different regions of the aspheric surface is obtained. The experimental result indicated that the distortion of the removal function is consistent with the theoretical result. Through this study, the distortion rule of aspheric removal function in the computer-controlled optical surfacing with pitch tool is finally mastered, which provides a theoretical guidance for the computer-controlled optical surfacing process optimization.

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Section: Calculation Methodsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Distortion of removal function based on the local asphericity of aspheric surface and the viscoelasticity of polishing tool in computer-controlled optical surfacing

Chen

Zhong

Wang

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part C:

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show abstract

“…[5][6][7] This is a wide-angle terrestrial telescope with a primary hyperbolic mirror 4100 mm in diameter and a secondary mirror 1240 mm in diameter, intended for surveying the Southern Hemisphere of the sky simultaneously in the visible and IR regions. The telescope has an altazimuth mount, and the image is formed at the Cassegrain focus.…”

Section: Testing the Primary Mirror Of The Vista Telescopementioning

confidence: 99%

“…6). The deviations from the vertex sphere are 4 mm, the vertex radius of the mirror must be obtained with an accuracy of 8094 20 mm, and the conic constant must be −1.129792 0.00005.…”

Section: Testing the Primary Mirror Of The Vista Telescopementioning

confidence: 99%

Interference methods of testing the surface figure of large aspheric items, based on lens-type and holographic wave-front correctors

Semenov¹,

Abdulkadyrov²,

Patrikeev³

et al. 2013

J. Opt. Technol.

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This paper discusses the features of methods of testing aspheric primary mirrors of telescopes with lens-based, mirror-lens-based, and holographic correctors. Methods are described for simultaneously testing the same surface of an optical item with different correctors to achieve and confirm the required parameters of the aspheric (vertex radius and conic constant). Results are given for testing the correctors with a holographic mirror simulator to verify the fabrication accuracy of the correctors themselves and, if necessary, of the wave-front correction of the lens correctors.

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Evolution law of comet-shaped defects in magnetorheological finishing

et al. 2022

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Ultraprecision optical systems such as high-energy laser systems have very strict requirements for surface defects of optical components. Comet-shaped defects are common in magnetorheological finishing, which is one of the main ultraprecision manufacturing technologies. Computational fluid dynamics is used to simulate the pressure and velocity of the magnetorheological fluid in pits during magnetorheological finishing for the first time, to the best of our knowledge. The simulation model analyzes the distribution of velocity and pressure in the process of the formation of comet-shaped defects. After the simulation, magnetorheological polishing experiments were carried out on the fused quartz silica glass. The polishing experiments use the rotation speed and immersion depth of the polishing wheel to verify the velocity and pressure distribution in the simulation experiment. The polishing experiment results are consistent with the simulation results, which show that the high polishing speed will increase the depth of the defect, and the uneven velocity and pressure distribution at the pits make the pits evolve into comet-shaped defects. We explain the cause of comet-shaped defects from the perspective of material removal and provide an optimization method of process parameters for high-efficiency removal of comet-shaped defects.

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Technological features of the fabrication of the primary mirrors of telescopes

Cited by 3 publications

References 8 publications

Distortion of removal function based on the local asphericity of aspheric surface and the viscoelasticity of polishing tool in computer-controlled optical surfacing

Distortion of removal function based on the local asphericity of aspheric surface and the viscoelasticity of polishing tool in computer-controlled optical surfacing

Interference methods of testing the surface figure of large aspheric items, based on lens-type and holographic wave-front correctors

Evolution law of comet-shaped defects in magnetorheological finishing

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