Hydrostatic support system for in-situ optical testing of a 4 m aperture SiC mirror

Hu, Haitian; Hong-wei, 赵宏伟 Zhao; Zhen-yu, 刘振宇 Liu; Xiao, 罗霄 Luo; Xue-jun, 张学军 Zhang

doi:10.3788/ope.20172510.2607

Cited by 5 publications

(1 citation statement)

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“…The gravity unloading system is shown in Fig. 13, which can effectively suppress the unloading deformation during the processing of the oversized mirror on the one hand, and provide the in-situ testing of gravity unloading function to ensure the consistency of the boundary conditions of the processing support and the mirror chamber support on the other hand [34][35] . Through the implementation of the above technique, the system will highly reduce the risk of frequent handling of large mirrors and significantly improve their manufacturing accuracy and efficiency.…”

Section: B) Hydro-unit Designmentioning

confidence: 99%

Challenges and strategies in high-accuracy manufacture of the world's largest SiC aspheric mirror

Zhang

2022

Preprint

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In consideration of the difficulties in the high-accuracy manufacture of the world's largest aperture SiC (silicon carbide) aspheric mirror, such as the difficulty of processing complex mirror blanks, low accuracy and efficiency of conventional processing, print-through effect, inconsistent processing and testing states, high stress/poor denseness of conventional cladding, the insufficient dynamic range of conventional measurement, and air turbulence of long optical path testing, we proposed the water-soluble room temperature vanishing mold and gel casting technology, homogeneous microstructure reaction-formed joint technology, nano-accuracy efficient convergence processing technology, gravity unloading technology, high-denseness low-defect PVD (Physical Vapor Deposition) cladding process, data fusion testing technology, time-domain averaging method, etc. On the basis of the proposed key technologies and methods, we have currently developed the world's largest SiC aspheric mirror with the size of ⌀4.03m. The impressive performance of the SiC aspheric mirror is verified as follows. The area density of the SiC blank is less than 120kg/m2; surface error testing accuracy is less than 6nm RMS; the thickness inhomogeneity of cladding layer is less than 5%; the final surface error and roughness are 15.2nm RMS and 0.78nm RMS, respectively.

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Section: B) Hydro-unit Designmentioning

confidence: 99%

Challenges and strategies in high-accuracy manufacture of the world's largest SiC aspheric mirror

Zhang

2022

Preprint

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Challenges and strategies in high-accuracy manufacturing of the world’s largest SiC aspheric mirror

Zhang

Wang

et al. 2022

Light Sci Appl

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In the process of manufacturing the world’s largest silicon carbide (SiC) aspheric mirror, the primary difficulties are mirror blank preparation, asphere fabrication, and testing, as well as cladding and coating. Specifically, the challenges include the homogeneity of the complicated structure casting, accuracy and efficiency of the fabrication process, print-through effect, fidelity and precision of test procedure, stress and denseness of cladding process, the dynamic range of interferometric measurement, and air turbulence error due to the long optical path. To break through such a barrier of difficulties, we proposed the water-soluble room temperature vanishing mold and gel casting technology, homogeneous microstructure reaction-formed joint technology, nano-accuracy efficient compound fabrication, gravity unloading technology, high-denseness low-defect physical vapor deposition (PVD) Si-cladding technology, test data fusion method, and time-domain averaging method, etc. Based on the proposed technologies and methods, we have accomplished the world’s largest SiC aspheric mirror with a size of ⌀4.03 m. The impressive performance of the SiC aspheric mirror is validated by the characteristics of the fabricated SiC aspheric mirror. The aerial density of the SiC blank is less than 120 kg/m2, surface shape test accuracy is better than 6 nm RMS, thickness inhomogeneity of the cladding layer is less than 5%, and the final surface figure error and roughness are 15.2 nm RMS and 0.8 nm RMS, respectively.

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Optimization design of an ultralight large-aperture space mirror

et al. 2021

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The ultralight space mirror has long been a hot topic in the research field of space telescopes. In this paper, an ultralight mirror is designed by obtaining the structure and parameters of a mirror with an aperture of 2 m through experimental design and multiobjective integrated optimization. Specifically, the materials near the neutral surface were replaced with elliptical holes. The back of the mirror was supported at three points. Finite-element analysis shows that the mirror had a surface figure error of 10.4 nm under 1 g in the x direction (gravity direction), which is sufficiently high to be applied to visible light optical systems. Further, the eigenfrequencies of mirror components were obtained through finite-element analysis: 70 Hz in the x direction, 70 Hz in the y direction, and 90 Hz in the z direction. The results demonstrate the excellent dynamics performance of the designed mirror. Compared with test results, the relative error of eigenfrequencies was within 4%. Hence, our ultralight design outputs reliable optimization results and applies to the development of large-aperture ultralight space mirrors. Finally, the ultralight mirror was prepared from reaction-bonded silicon carbide. The mass and surface density of the prepared mirror were 105 kg and 34 k g / m 2 , respectively. The mirror mass was 50% lighter than that of the mirrors designed by traditional lightweight methods.

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Hydrostatic support system for in-situ optical testing of a 4 m aperture SiC mirror

Cited by 5 publications

References 0 publications

Challenges and strategies in high-accuracy manufacture of the world's largest SiC aspheric mirror

Challenges and strategies in high-accuracy manufacture of the world's largest SiC aspheric mirror

Challenges and strategies in high-accuracy manufacturing of the world’s largest SiC aspheric mirror

Optimization design of an ultralight large-aperture space mirror

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