25 August 1998 Status of the coating facility of the Subaru Telescope
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Abstract
One of the major problems to retain the efficiency of a telescope is to achieve and maintain high reflectivity in the wide wavelengths of the coatings of the telescope optics. For coating the large mirrors of Subaru Telescope, we employed the conventional evaporation scheme, in the expectation of uniform coverage of the film. In this paper, we will report the installation and the performance verification of the coating facility. This facility consists of a washing tower for stripping off the old coating, an evaporation coating chamber, two trolleys and a scissors- like lifter for handling the primary mirror. To supply a large number of filaments loaded with uniform quality molten metal, the practical solution is to pre-wet the filaments with the agent metal and keep them in a controlled manner before the evaporation. The aluminum film deposit on the test samples in the 8.3 m coating chamber proved the film thickness uniformity matching with the specification. Reflectivity of the fresh surface was over 90% at visible wavelength. In September 1997, we re-aluminized 1.6 m and 1.3 m mirrors for the first time (at least for ourselves) application to the real astronomical telescopes. The resultant surface reflectivity confirmed the feasibility of using pre-wetted filaments.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Saeko S. Hayashi, Yukiko Kamata, Tomio Kanzawa, Akihiko Miyashita, Masao Nakagiri, Tetsuo Nishimura, Takeshi Noguchi, Kiichi Okita, Norio Oshima, Goro Sasaki, Yasuo Torii, Masami Yutani, Tsuyoshi Ishikawa, "Status of the coating facility of the Subaru Telescope", Proc. SPIE 3352, Advanced Technology Optical/IR Telescopes VI, (25 August 1998); doi: 10.1117/12.319267; https://doi.org/10.1117/12.319267
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