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SUBARU Telescope

Location of SUBARU Telescope

Large Size
Optical Infrared Telescope
-Nickname SUBARU Telescope-

   SUBARU telescope is located a little north of the center of Hawaii island, the largest of all the islands that form the state of Hawaii, the 50th state of the United States. SUBARU telescope of the National Astronomical Observatory of Japan is located on top of Mt. Mauna Kea at an altitude of 4,205m. The main mirror with a diameter of 8.3 meters makes the large size infrared telescope the world's largest refining telescope.
      Its total construction took 400 million US dollars, and when it started its test observation in January of 1999, the project was called Japan National Large Telescope, JNLT. Its nickname of SUBARU was selected from a public offering conduced in 1991 when the construction started.
SUBARU telescope       SUBARU telescope has compiled a number of state-of-the-art technologies. One of such technologies is the nano-technology by NALUX applied in optically correcting the main mirror. 261 computer-controlled actuators push the main mirror from the backside to maintain its ideal form.

SUBARU Telescope

Subaru Telescope Improves its Eyesight by a Factor of Ten

(The following passages are extracted from the November 20, 2006 press release on the official website of National Astronomical Observatory of Japan with their consent)

      Subaru's adaptive optics development team has been working on upgrading its older 36-element adaptive optics system with an improved 188-element system for the past five years. At the same time, the team also developed and installed a new laser guide star system that allows astronomers to create an artificial star anywhere in the sky. They use light from the artificial star to measure the twinkle brought on by the atmosphere. The adaptive optics system then takes the information to deform a special mirror that removes the twinkle and clarifies the view.

      The 188-element adaptive optics system allows Subaru to reach its diffraction limit, the theoretical limit of its resolving power determined by the size of its primary mirror (and the wavelength of light in question). Dr. Hideki Takami led the development and implementation of this system. The two main components of the AO system are the wavefront sensor that analyzes the light from the guide star, and the deformable mirror that corrects the light from the target object for any measured distortion in the light from the guide star. The wavefront sensor has a lenslet array that divides the light from the guide star into 188 parts. A super-sensitive detector with avalanche photo diodes capable of measuring individual photons senses the brightness in each of these parts at high speed. The variation in brightness is used to determine the distortion in the wavefront of light from the guide star, and then to adjust the shape of the deformable mirror to counter the distortion. Such adjustments are made a thousand times a second. During the test observations on October 9, 2006, the adaptive optics system successfully removed atmospheric blurring and shrank an image of a star from 0.6 arcseconds to 0.06 arcseconds.

Schematic diagram of adaptive optics
Schematic diagram of adaptive optics (NAOJ)