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Proceedings Paper

Conceptual design of 1.5m aperture vertical collimator assembly with short tube and long focus
Author(s): Fei Yang; Ming Ming; Fu-guo Wang; Li-min Zhang; Bao-gang Chen; Liang Shao
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Paper Abstract

In order to evaluate and test the image quality of large aperture telescope, the most directly method is adopting the collimator and test the telescope system with full aperture. Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) commenced developing the large aperture collimator for interferometric and image quality testing of meter scale optical systems under cryogenic, vacuum conditions. The aperture of the collimator which has been on the conceptual design phase is 1.5m diameter, and the optical configuration is Cassegrain, the focus is 50m. The material of reaction bonded Silicon Carbide (RB-SiC) produced by CIOMP will be used as the primary mirror substrate. And the figure accuracy of the primary mirror will be polished better than 15nm (RMS). The collimator will be working in a vacuum chamber and face down vertically to the unit under test. The application requirements, specification requirements, and some key technology are demonstrated and analysed with finite element analysis (FEA) in the paper. The feasibility, error budget, and hazards evaluation of the collimator are fulfilled by the FEA results. It demonstrated that the conceptual design meet the requirements of the 1.5m aperture vertical collimator, and could achieve the high accuracy requirements of the wavefront for the beam of light in the vacuum chamber, which the wavefront error should less than 32nm(RMS). Mechanical alignment errors induced by thermal and structural perturbations are monitored with an auto-focusing system to enable focus compensation. The ambient temperature of the collimator in chamber are controlled allowing testing while the chamber shrouds and test unit are brought to cryogenic temperatures. With the high accuracy of the wavefront, the collimator could test the image resolution, modulation transfer functions (MTFs), point spread functions (PSFs), encircled energy, wavefront error, best focus, etc. for optical systems. And the conceptual design could be consulted to other large aperture collimators.

Paper Details

Date Published: 11 September 2013
PDF: 9 pages
Proc. SPIE 8907, International Symposium on Photoelectronic Detection and Imaging 2013: Infrared Imaging and Applications, 89071C (11 September 2013); doi: 10.1117/12.2032307
Show Author Affiliations
Fei Yang, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Ming Ming, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Fu-guo Wang, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Li-min Zhang, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Bao-gang Chen, Changchun Institute of Optics, Fine Mechanics and Physics (China)
Liang Shao, Changchun Institute of Optics, Fine Mechanics and Physics (China)


Published in SPIE Proceedings Vol. 8907:
International Symposium on Photoelectronic Detection and Imaging 2013: Infrared Imaging and Applications
Haimei Gong; Zelin Shi; Qian Chen; Jin Lu, Editor(s)

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