Abstract
Subaru telescope has been leading the world as the best instrument for astronomical observation in the visible and infrared region. Before Subaru, Japan had almost no experience to engineer and design such a large and accurate optical telescope. At the development stage, various state-of-the-art technologies were studied. It is, however, the basis of "The mechanics of materials" that played one of the most important roles in the study. The important roles include 1) how to make the huge and complicated telescope structure behave as an elastic body so as to show almost perfect repeatability of the deformation, and 2) how to obtain force vectors to correct the deformation of primary mirror with 8.3m diameter. This is to simplify the drive control system of the telescope structure and the figure control system of the primary mirror. The author learnt "The mechanics of materials" and "The theory of elasticity" from Prof. Atsumi in Tohoku University late in the 1970s, and led the Subaru telescope project as a system engineer and project manager in Mitsubishi Electric from 1987 to 2001. The basis of the learning was fully utilized in the design of Subaru with some additional application which Prof. Atsumi would have not taught. Some differences of the practical engineering from the academic learning and some key technologies which led the success of Subaru are introduced.
