[meteorite-list] Next Generation of Adaptive Optics Arrive at the Large Binocular Telescope

[Ron Baalke]

http://intelligencer.ccit.arizona.edu/node/32405

FOR IMMEDIATE RELEASE
FROM THE UNIVERSITY OF ARIZONA

June 16, 2010

Contact information follows this story.

The Universe, Crisp and Clear

The next generation of adaptive optics has arrived at the Large  
Binocular Telescope in Arizona, providing astronomers with a new level  
of image sharpness surpassing that of the Hubble Space Telescope.

The next generation of adaptive optics has arrived at the Large  
Binocular Telescope in Arizona, providing astronomers with a new level  
of image sharpness never before seen.

Developed in a collaboration between Italy's Arcetri Observatory of  
the Istituto Nazionale di Astrofisica, or INAF, and the University of  
Arizona's Steward Observatory, this technology represents a remarkable  
step forward for astronomy.

"This is an incredibly exciting time as this new adaptive optics  
system allows us to achieve our potential as the world's most powerful  
optical telescope," said Richard Green, director of the LBT. "The  
successful results show that the next generation of astronomy has  
arrived, while providing a glimpse of the awesome potential the LBT  
will be capable of for years to come."

Until relatively recently, ground-based telescopes had to live with  
wavefront distortion caused by the Earth's atmosphere that  
significantly blurred the images of distant objects (this is why stars  
appear to twinkle to the human eye). While there have been  
advancements in adaptive optics technology to correct atmospheric  
blurring, the LBT's innovative system takes this concept to a new level.

This success was achieved through the combination of several  
innovative technologies. The first is the secondary mirror, which was  
designed from the start to be a main component of the LBT rather than  
an additional element as on other telescopes. The concave secondary  
mirror is .91 meters in diameter (3 feet) and only 1.6 millimeters  
thick.

The mirror is so thin and pliable that it can easily be manipulated by  
actuators pushing on 672 tiny magnets glued to the back of the mirror,  
which offers far greater flexibility and accuracy than previous  
systems on other telescopes. An innovative "pyramid" sensor detects  
atmospheric distortions and manipulates the mirror in real time to  
cancel out the blurring, allowing the telescope to literally see as  
clear as if there were no atmosphere.

Incredibly, the mirror is capable of making adjustments every one  
thousandth of a second, with accuracy to better than 10 nanometers (a  
nanometer is one millionth the size of a millimeter).

In closed-dome tests beginning May 12 and sky tests every night since  
May 25, astronomer Simone Esposito and his INAF team tested the new  
device, achieving exceptional results.

The LBT's adaptive optics system, called the First Light Adaptive  
Optics system, or FLAO, immediately outperformed all other comparable  
systems, delivering an image quality greater than three times sharper  
than the Hubble Space Telescope using just one of the LBT's two 8.4  
meter mirrors. When the adaptive optics are in place for both mirrors  
and their light is combined appropriately, it is expected that the LBT  
will achieve image sharpness 10 times that of the Hubble.

The index of the perfection of image quality is known as the Strehl  
Ratio, with a ratio of 100 percent equivalent to an absolutely perfect  
image. Without adaptive optics, the ratio for ground-based telescopes  
is less than 1 percent. The adaptive optics systems on other major  
telescopes today improve image quality up to about 30 percent to 50  
percent in the near-infrared wavelengths where the testing was  
conducted.

In the initial testing phase, the LBT's adaptive optics system has  
been able to achieve unprecedented Strehl Ratio of 60 to 80 percent, a  
nearly two-thirds improvement in image sharpness over other existing  
systems.

The results exceeded all expectations and were so precise the testing  
team had difficulty believing its findings. However, testing has  
continued since the system was first put on the sky on May 25, and the  
LBT's adaptive optics have functioned flawlessly and achieved peak  
Strehl Ratios of 82 to 84 percent.

"The results on the first night were so extraordinary that we thought  
it might be a fluke, but every night since the adaptive optics have  
continued to exceed all expectations. These results were achieved  
using only one of LBT's mirrors. Imagine the potential when we have  
adaptive optics on both of LBT's giant eyes," Esposito said.

More images from the adaptive optics system are available at the LBT  
Observatory website.

Development of the LBT's adaptive optics system took longer than a  
decade through an international collaboration. INAF, in particular the  
Arcetri Observatory, conceived the instrument design and developed the  
electro-mechanical system, while the University of Arizona Mirror Lab  
created the optical elements, and the Italian companies Microgate and  
ADS International engineered several components.

A prototype system was previously installed on the Multiple Mirror  
Telescope, or MMT, at Mt. Hopkins, Ariz. The MMT system uses roughly  
half the number of actuators as the LBT's final version, but it  
demonstrated the viability of the design. The LBT's infrared test  
camera, which produced the accompanying images, was a joint  
development of INAF in Bologna and the MPIA in Heidelberg.

"This has been a tremendous success for INAF and all of the partners  
in the LBT," said Piero Salinari, research director at the Arcetri  
Observatory, INAF. "After more than a decade and with so much care and  
effort having gone into this project, it is really rewarding to see it  
succeed so astoundingly."

The $120 million LBT on Mount Graham utilizes two giant 8.4 meter  
mirrors and with the new adaptive optics the telescope will have the  
resolution of a 22.8-meter, or approximately 75-foot telescope. The  
new adaptive optics will enable versatile instruments such as the near- 
infrared camera spectrometer, which allows astronomers to penetrate  
interstellar dust clouds and reveal the secrets of the youngest and  
most distant galaxies, to achieve their full potential on the LBT.

The LBT is an international collaboration among institutions in the  
U.S., Italy and Germany. The LBT Corporation partners are:

The University of Arizona on behalf of the Arizona university system
Istituto Nazionale di Astrofisica, Italy
LBT Beteiligungsgesellschaft, Germany, representing the Max Planck  
Society, the Astrophysical Institute Potsdam, and Heidelberg University
The Ohio State University
The Research Corporation, on behalf of The University of Notre Dame,  
University of Minnesota and University of Virginia
###

CONTACTS:

Richard Green, Large Binocular Telescope Observatory (520-626-7088; rgreen at as.arizona.edu 
)

Jennifer Fitzenberger, University Communications (520-621-9017; jfitzen at email.arizona.edu 
)