Large Binocular Telescope Achieves Optics Breakthrough

June 30, 2010 — One of the world's most powerful telescopes, the Large Binocular Telescope in Arizona – of which the University of Virginia owns a share – has achieved a milestone by effectively ifying the blurring effects of the Earth's atmosphere and providing some of the clearest images ever of cosmic bodies.

Listen to the UVA Today Radio Show report on this story by Fariss Samarrai:

Recent images are sharper and clearer than similar views taken from the Hubble Space Telescope.

Normally, cosmic objects are blurred by wavering patterns caused by temperature changes in the Earth's atmosphere, making the imaging of objects less sharp than desired. To reduce this effect, most research telescopes, including the Large Binocular Telescope, are located on mountaintops in remote desert or semi-arid environments. Space telescopes, such as the Hubble, though difficult and expensive to maintain and repair, are able to capture crisp images of the cosmos because of their locations outside of Earth's atmosphere.

The Large Binocular Telescope is located on Mount Graham in Arizona's Coronado National Forest, where the air is relatively clear. A new technology, built in to a secondary mirror of the telescope, counteracts the blurring effects of the atmosphere.

"What the LBT project did, which is different from all other Earth-bound telescope projects, is to build a correction into its secondary mirror," said astronomy professor Robert O'Connell, U.Va.'s representative to the project. "The mirror is continually adjusted, at a rate up to a thousand times per second."

The new computer-driven device includes 672 pistons that continually alter the shape of the mirror's thin glass surface to correct for the tiny changes in temperature that cause image blurring. These minute adjustments occur at a scale of about 1/10th of a micron, O'Connell said.

"This capability was under development for 10 years, but only in the last two months has it been deployed and made functional," he said. "It's working perfectly, producing images so far that are as good as, if not better than, anything we've obtained from the Hubble Space Telescope."

The capability is still in its test phase, O'Connell said, but eventually will be used for all observing over the course of the planned multi-decade life of the telescope.

The Large Binocular Telescope is really two telescopes on a common mount spanning 74 feet, each with a 27-foot diameter primary mirror and its own secondary mirror. Eventually both telescopes will work together to form a single image, equivalent to what would be possible from a much larger telescope. That combination of two telescopes acting as one, as a so-called "interferometer," will improve viewing capability by another factor of three, O'Connell said.

"When fully operational, the LBT will produce images about five times sharper than the Hubble Space Telescope. Of course, Hubble has capabilities unattainable from the ground, such as observing in the ultraviolet spectrum, which cannot be done from Earth."

The eventually fully capable Large Binocular Telescope will be used to resolve individual planets' orbiting stars, allowing astronomers, potentially, to discover Earth-sized planets in other solar systems, including ones that possibly could support life. It also will offer clear views to the edge of the universe, including the most distant, faintest and youngest galaxies.

"We're very excited," O'Connell said. "This really is a great step forward and we're eager to get our hands on this capability."

The Large Binocular Telescope will overcome many of the technological and physical barriers that have limited ground-based astronomy. Its two giant mirrors will give a deeper and clearer view of the cosmos than has ever been achieved. By combining light beams from the two mirrors, the telescope can collect light at the same rate as a single mirror 38 feet across and is expected to show detail on as fine a scale as a single-mirror telescope 74 feet across. Currently the world's largest single-mirror telescope is 36 feet across, but has limited pointing capability and carries few instruments.

About a dozen U.Va. astronomers are involved in research and other projects with the Large Binocular Telescope, and U.Va. astronomers currently are building a specialized infrared camera that will be part of the next phase of high-resolution development of the telescope. That instrument likely will be mounted in September to undergo testing.

The facility is owned and operated by a consortium of universities in the United States, Italy and Germany. U.Va. became a member in 2002. The telescope achieved "first light" in October 2005, when it captured images of a spiral galaxy 24 million light years away.

— by Fariss Samarrai