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Green light for the construction of the 19-m aperture giant European Extremely Large Telescope (E-ELT) has been given by the European Southern Observatory council on Dec 4th, 2014. Procurement of the key elements was immediately initiated by ESO team and Safran Reosc has been awarded several optical polishing and testing contracts since that time : in July 2015 the contract for the Adaptive Optics M4 thin glass petals, in July 2016 the contract for the 4-m M2 convex mirror and in Feb 2017 the contract for the 4-m M3 mirror.
We will highlight the challenges linked to these various optical fabrication projects and report about the progress of our work so far.
14:15 - 14:30 Invited
Optical System of the WSO-UV Space mission telescope
Institute of Astronomy RAS, Russian Federation
The World Space Observatory--Ultraviolet (WSO--UV) project is a Russian-Spanish space mission for spectroscopic and imaging observations in the UV domain (115-310 nm) where some of the most important astrophysical processes can be efficiently studied with unprecedented capability. In the horizon of the next decade, WSO--UV will be the only mission with the large primary mirror fully devoted for UV studies.
The observatory includes a 170 cm aperture telescope capable of high-resolution spectroscopy, long slit low-resolution spectroscopy, and deep UV imaging. The telescope T-170M is a Ritchey-Chrétien with a F/10 focal ratio and a corrected field of view of 0.5 degrees. Here we present results of primary mirror tests.
14:30 - 14:45
Optimization of Structure and Manufacturing Capabilities of Light-Weighted Mirrors Production
Magomed A. Abdulkadyrov, Nikita M. Vladimirov, Nikolay S. Dobrikov, Aleksandr N. Ignatov, Vladimir E. Patrikeev, Aleksandr P. Semenov
JSC LZOS/ Russia, Russian Federation
The main stages of selection and optimization of the extra-light-weighted mirrors structure is selecting the material and defining the type and cell parameters of the light-weighting structure. Optimization of mirrors structure based on the calculation by finite element method allows defining the optimal parameters of cells of the light-weighting structure with the aim of obtaining the maximum structure stiffness with minimum weight. The variable parameters are thickness of the working surface, size and shape of the cells of the light-weighting structure and ribs thickness.
14:45 - 15:00 Invited
Manufacturing large aperture and high diameter-to-thickness ratio flat mirror as the prototype of TMT M3
Xue-jun Zhang, Hai-xiang Hu, Xiao Luo, Er-hui Qi, Hai-fei Hu
Changchun Institute of Optics, Fine Mechanics & Physics, People's Republic of China
Large flat mirrors play important roles in modern astronomical telescopes. Designed to be the largest optical flat, the tertiary mirror (M3) of the Thirty Meter Telescope (TMT) has a very high diameter-to-thickness ratio. It is very challenging to fabricate this 'soft‘ mirror to a high accuracy and smoothness as required, particularly in CCOS method. In this paper, a dual support system was developed at first. Semi-deterministic figuring and smoothing techniques were addressed in detail. In order to make high accuracy flat efficiently, on-situ sub-aperture stitching interferometer and pentaprism scanning equipment was applied. Finally, the results for the tertiary mirror prototype were presented.
15:00 - 15:15
The MESSIER path finder: a high performance, wide field, fast and distortion free telescope using a curved detector
Eduard Muslimov1,2, Emmanuel Hugot1, Xin Wang3, David Valls Gabaud4, Pascal Vola1, Gérard R. Lemaitre1
1Aix Marseille Univ, CNRS, LAM, Laboratoire d'Astrophysique de Marseille, Marseille, 13388 France; 2Kazan National Research Technical Univ.-KAI,Optical&electr. syst. Dept. ,Kazan, 420111 Russia; 3Shanghai Institue of Technical Physics - SITP, No. 500 Yutian Road, Shanghai 200083, China; 4Institut d’Astrophysique de Paris, 98 bis, Bld Arago, Paris, 75014 France
We present optical design of a high-quality, 36-cm diameter, fast (F/2.5) VIS telescope with a large field of view (1.6°x2.6°) developed for space science applications. The design is based on a bi-folded all-reflective Schmidt scheme using a curved detector. We demonstrate its advantages in terms of optical quality and manufacturability.
15:15 - 15:30
Rapid fabrication strategy for 1.5m OAP using CCOS method
Hai-xiang Hu, Er-hui Qi, Xiao Luo, Xue-jun Zhang
Changchun Institute of Optics, Fine Mechanics & Physics, China, People's Republic of
Off-axis paraboloid parts (OAP) or quasi-OAP are mostly frequently used in large optical telescopes. Compared with the stressed mirror polishing, CCOS method or other computer-controlled subaperture tools provide more flexibility. However, it is the very need to promote its fabrication efficiency in tactic ways. In the paper, we present a large aperture CCOS tool using a compound motion unit, and go through the grinding and pre-polishing with its figure errors and edge effects well controlled. In fine polishing stage, CCOS tool, MRF, and IBF are applied in combination to finish. We experimental test this strategy on a 1.5m OAP, as a part of Giant Steerable Science Mirror (GSSM) program in the Thirty Meter Telescope (TMT).