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UH astronomers develop
By Helen Altonn
the world's largest
infrared image detector
Star-Bulletin
A device capable of detecting galaxies created at the beginning of the universe has been developed under the leadership of University of Hawaii astronomers.
It is the world's largest infrared image detector -- so sensitive it can record images below one-billionth the level of typical room light.
A consortium of UH-led universities funded the detector's development at the Rockwell Science Center in Thousand Oaks, Calif.
UH astronomers Donald N.B. Hall and Klaus Werner Hodapp, both based in Hilo, have worked with Rockwell for nearly 10 years "to keep developing this technology, to develop successively larger and more powerful devices," Hall said.
The first of the new devices was funded through the Air Force and is being sent to the Hawaii Institute for Astronomy for use at the Air Force telescope on Haleakala, Maui, said Hall, a former director of the institute.
The European Southern Observatory and the Subaru Telescope -- the other two consortium members -- will receive sensors to use with their giant telescopes in Chile and on Mauna Kea on the Big Island.
Sensing celestial heat
The new sensor is a square with 2,048 pixels to a side, meaning it has nearly 4.2 million pixels, or picture elements.It also has more than 13 million transistors.
It can detect small amounts of heat radiated from distant celestial bodies.
"Optical light is where our stars get most of their light," Hodapp explained.
"As you look back into the early universe, you're looking at higher and higher 'red shifts,' which means the galaxies seem to be flying away from us at increasing speed."
The earliest galaxies can be detected by shifting from optical light to the infrared wavelength, he said.
The new detectors also will permit a clearer view of what's going on in obscured core regions of our own and other galaxies, Hodapp said.
The UH astronomers have had a significant role in detector advances for astronomy research.
Hodapp headed the team that worked with Rockwell to create the first infrared array, with 1 million pixels, in 1994.
It was used on UH's 88-inch telescope on Mauna Kea to study Comet Shoemaker Levy 9's crash into Jupiter.
"We were able for the first time to routinely take infrared images with all of the detail of a high-resolution computer monitor," Hall said.
About 30 of the 1 million-pixel detectors are being used on telescopes around the world, revolutionizing infrared astronomy, he said.
Thirty years ago in infrared astronomy, Hall recalled, "We made pictures by scanning a single crystal detector around the sky." Hodapp said he started with a minuscule 32-square-inch detector.
'Very detailed pictures'
Now, Hall said, "We have this device that has three or four times the pixels, or image detail, of a high-resolution video monitor and is actually approaching the detail of an IMAX image."
One of the advantages of the large detectors is that telescopes can be used more efficiently, Hodapp said.
Instead of piecing together images from many individual exposures, he said, "We can take very detailed pictures of objects and wider fields of sky."
The UH team is building a spectrograph specifically for the Air Force telescope to see large portions of the spectrum in one exposure, Hodapp said.
Rockwell is developing sensors for a new infrared camera for the Hubble Space Telescope and the Next Generation Space Telescope.
Also in planning is a larger, 4,096-by-4,096 infrared sensor.
"Requirements for the Next General Space Telescope are to take devices like this, which already stretch most astronomers' imagination, and to use them like tiles to make up what we call a mosaic to get a total of around 100 million pixels," Hall said.
The Next Generation Space Telescope will be an 8-meter telescope, the size of the largest on Mauna Kea, Hall noted. It will be launched in 2007 or 2008, and go "well beyond the moon," he said.
Hodapp said the Keck Observatory group is pushing for a 4,096-square detector array. "But first we have to stabilize development of 2,000 squares.
"It's one thing to produce one device, and another to produce 50 and distribute them around the world," he said, noting a long list of customers interested in buying the newest sensors.
Hall points out that quadrupling the number of pixels for observations provides "the same huge gain as increasing the telescope area by a factor of four. It is obvious what gains the new array will provide."
And the development came in just six years, he said.
"It took over half a century to jump from the 200-inch Palomar telescope to the 10-meter (400-inch) Keck on Mauna Kea."
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