Ultra Large Telescope TMT

Next fiscal year starts preparation " TMT (Thirty Meter Telescope) " very large telescope of the next generation is in progress . 5 countries, including Japan and the United States during the construction of the U.S. Hawaii Mauna Kea summit , the giant telescope of 30 m diameter as its name suggests . I will introduce a plan to make use of high technology in Japan , explore the depth of space .
● ultra-high-performance glass development
Primary mirror of the telescope , which plays an important role to collect the light of the star . Rather than a mirror of one , the primary mirror of TMT huge form side-by-side 492 pieces of hexagonal mirror Sashiwatashi 1.44 m , 45 mm thick , 175 kg of weight . There is a gap of 2.5 mm (the gap ) between the plates and the plate , and a mechanism to adjust precisely the drive mechanism the orientation of each plate so that it is a single concave mirror as a whole .
Optical and special glass manufacturer " O'Hara " had received an order for production of 82 pieces of the first , but ( Sagamihara ) . So that the celestial body image is not distorted , technology ( brand name, CLEARCERAM Z) was bought zero expansion glass that does not expand even if the temperature is raised . Above and below the 1 degree temperature , I is suppressed to within 0.00002 mm slight expansion and contraction of the glass of one meter length .
Was dissolved in about 1600 ° to mix metal oxide glass, and solidified by quenching to maintain for a long time about 800 degree glass is not melted by reheating . Thus , crystals of the metal oxide can be uniformly into the glass, and that he be zero expansion and shrinkage force of the crystals and the expansion force of the glass is canceled out by the temperature increase . While the least , increase the technology in strict product standards , such as camera , to corner the world's most advanced now in this field . However , development of for TMT large uniform in flame business, " larger , difficult to keep the uniform . Spent five years to double the 80 cm diameter of traditional maximum " South River and specialty products business manager and said. Future , mirror surface coating that is applied in Hawaii through the process a number of cutting and scraping , and finishing .
● 4 times the resolution Subaru
According to the National Astronomical Observatory of Japan , TMT has a light-gathering capability of about 10 times the telescope of 8-10 m class diameter of maximum current , resolution performance is about four times ( Hawaii , diameter 8.2 m ) of the Subaru telescope . The light collected by the primary mirror enters the observation device by reflecting the secondary mirror , the third mirror. In addition to using the infrared light and visible light , and space close to birth history by observing stars and galaxies farther than ever , with the aim of direct observation of Earth -like planets .
Scheduled for completion in fiscal 2022 . Total construction cost is about 150 billion yen , Japan plans to contribute a quarter , responsible for the production of the body . Aoki 's National Astronomical Observatory of Japan TMT Promotion Office to emphasize " it took nearly 30 years in the past diameter is to be doubled , but it is progress . Revolutionary 3 -fold in 30 years time" and .
Ultra Large Telescope TMT that come along by the height of the technology in Japan , I want to clarify the state of the universe at the time of the Big Bang and to demonstrate not regret the ability to have .



次世代の超大型望遠鏡「ＴＭＴ　（Ｔｈｉｒｔｙ　Ｍｅｔｅｒ　Ｔｅｌｅｓｃｏｐｅ）」の来年度着工準備が進んでいる。その名の通り直径３０メートルの巨大望遠鏡を、日米中など５カ国が米ハワイ島マウナケア山頂に建設する。日本の高い技術を生かし、宇宙の深奥を探る計画を紹介する。
　●超高性能ガラス開発
　星の光を集める重要な役割を担う望遠鏡の主鏡。巨大なＴＭＴの主鏡は１枚の鏡ではなく、差し渡し１・４４メートル、厚さ４５ミリ、重さ１７５キロの六角形の鏡４９２枚を並べて形作る。板と板の間には２・５ミリの隙間（すきま）があり、全体で１枚の凹面鏡になるよう各板の向きを駆動機構で精密に調整する仕組みだ。
　最初の８２枚の製造を受注したのが、光学・特殊ガラスメーカー「オハラ」（相模原市）だ。天体像がゆがまないよう、温度が上がっても膨張しないゼロ膨張ガラス（商品名・クリアセラムＺ）の技術が買われた。温度１度の上下で、長さ１メートルのガラスの膨張・収縮はわずか０・００００２ミリ以内に抑えられる。
　ガラスに金属酸化物を混ぜて約１６００度で溶かし、急冷して固めた後、再加熱してガラスが溶けない約８００度を長時間保つ。これにより、金属酸化物の結晶がガラスの中に均一にでき、温度上昇でガラスの膨張力と結晶の収縮力が打ち消し合ってゼロ膨張になるのだという。この分野では後発ながら、カメラ用などの厳しい製品基準で技術を高め、今や世界最先端の一角に。しかし、均一で大きなＴＭＴ用の開発は難事業で、南川・特殊品営業課長は「大きくなるほど、均一を保つのが困難。従来最大の直径８０センチを倍増するのに５年を費やした」と語る。今後、削りや裁断、仕上げなど数々の工程を経てハワイで鏡面塗装が施されるという。
　●解像度すばるの４倍
　国立天文台によると、ＴＭＴは現在最大の直径８〜１０メートル級の望遠鏡の約１０倍の集光能力を持ち、解像性能は、すばる望遠鏡（ハワイ、直径８・２メートル）の約４倍。主鏡で集めた光は副鏡、第３鏡で反射して観測装置に入る。可視光と赤外光を使い、従来より遠い星や銀河を観測して宇宙誕生史に迫るほか、地球型惑星の直接観測を目指す。
完成予定は２０２２年度。総建設費は約１５００億円で、日本は４分の１を拠出し、本体の製作を担う計画だ。国立天文台ＴＭＴ推進室の青木さんは「直径が２倍になるのに従来は３０年近くかかったが、今回は３０年で３倍。画期的な進歩だ」と強調する。
　日本の技術の高さによって出来上がる超大型望遠鏡TMTが、その持つ能力を遺憾なく発揮してビッグバン当時の宇宙の様子を明らかにしてほしいですね。