Posted: October 23, 2008
A zero-noise detector is in store for the future Thirty Meter Telescope (TMT) that will have a light-collecting power ten times that of the largest telescopes now in operation.
The detector's new sensing technology promises to penetrate the darkness of space with the greatest sensitivity ever. Often imaging sensors produce a ‘noisy’ signal that can degrade the quality of the image so much as to mean the difference between making a scientific discovery or not. According to Donald Figer of the Rochester Institute of Technology (RIT), who will lead the project in creating the zero-noise detector, it will have the same sensitivity as a combination of today's detectors and a 60 metre telescope for probing the farthest reaches of the Universe.
"You could quadruple the power of a telescope just by using this detector," says Figer. "Or you can do the same thing by making a telescope twice the size, but then we're talking a cost of billions of dollars and taking on a monumental engineering challenge."
The next generation Thirty Meter Telescope will have a light-collecting power over ten times that of the largest telescopes of this decade. It's set to see 'first light' in 2018, and will help astronomers look back to the very early Universe. Image: TMT.
Figer will lead a team of scientists from RIT and Massachusetts
"Don's detector research represents a technological leap forward for astrophysics and for a variety of industrial and commercial applications, as well," says RIT President Bill Destler.
The success of the detector rests on solving the problem of noise, which is a product of the device itself and especially problematic in low-light conditions. A way around the problem is to design a device using a digital photon counter to chart every single unit of light — or photon — coming from a given target. Basic technology to do this is already used for LIDAR (Light Detection and Ranging) applications that detect pulses of light, or bunches of photons.
"What we're trying to do is to detect single photons, each producing a much smaller pulse than the big packet of photons in the LIDAR applications," explains Figer. "So, we're going to have to go back to the basic engineering and figure out the things that need to be modified in the design to make it more capable of detecting single photons."
The detector will be put through its paces at cryogenic temperatures in the Rochester Imaging Detector Laboratory, which will help freeze out another potential source of noise, dark current. In the second phase of the project, Figer's team will adapt the detector technology to infrared applications, replacing silicon, a material sensitive only in optical light, with the semiconductor material Indium Gallium Arsenide (InGaAs). The infrared version of the detector will give astrophysicists the ability to peer through cosmic dust and also to detect stars in the early Universe.
"If you want to look back into the early Universe, you have to look back into the infrared," Figer says. The TMT will be able to study the internal properties of small distant galaxies, seen as they were when the Universe was young.
The detector research will take place under an award of $2.8 million presented to the RIT by the Gordon and Betty Moore Foundation, and when completed in the latter half of the next decade, TMT's large aperture and improved optics will produce images with an angular resolution three times better than the 10 metre Keck and 12 times better than the Hubble Space Telescope, at similar wavelengths.