BASIC RESEARCH OF LIGHT-WEIGHT OPTICS USING POLYMER MEMBRANE MIRRORS

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A very large and ultra lightweight space telescopes are needed for the far-inflrared astronomy to reach the resolution similar to that in the optical wavelength region. The traditional rigid telescopes can not be used any more because of their large weight. Mirrors made of flexible thin films or semi-ridig panels with an active support system are needed. Similar membrane mirrors are also used in the X-ray astronomy. The nested thin foil mirrors provide a teselscope with large collecting area. The current x-ray telescope, however, has not a good enough angular resolution, because of large shape errors in those thin foils. We studied the membrane materils, how construct mirrors, and how control the mirror shape, etc.Considering scientific objectives in X-ray astronomy, we conclude that a high-throughput grazing incident telescope with medium angular resolution of 4-2 arcsec is necessary. Most realistic idea to satisfy our requirements is a multiple coaxial-and-confocal nested Walter-type … More -1 optics with thin and highly precise mirrors, which are replicated from super-high precision mandrels. Although the Europian XMM project realized precise thin replica mirrors produced by a nickel electro-forming technique, we must, for future missions, research new lightweight replicant material which can form a precise surface by the replica technique. In this study, we arranged facilities and studied the polymers as a solution to realize those telescopes.The most realistic way to realize the large-aperture space infrared telescopes is to use a light-weighted C/SiC mirror attached to the CFRP honeycomb structure through an active support system. This type of telescope weighs 10 - 20 kg/m^2. When we need a lighter mirror, a single honeycomb panel made of pitch-based CFRP is most promising. That material has a very low thermal expansion and a very high thermal conductivity. We need to develop, in this case, the polishing or replica technics to make a high-precision surface with the CFRP.If we need a ultra lightweight mirror with <l kg/m^2, a polymer membrane mirror is the unique solution. However, a material which meets all the requiments (high surface flatness, UV rigidization, active surface control capability) is not available at present. Less